Laser welding device and laser welding method

Abstract

To suppress deviation of an emission position of measurement light with respect to an emission position of laser light when a posture of a laser head is changed.SOLUTION: A laser head 30 emits laser light L and measurement light S having a wavelength different from that of the laser light L to a workpiece 60. An optical interferometer 20 receives the measurement light S reflected by the workpiece 60 and measures a penetration depth of the workpiece 60. An adjustment mechanism 40 adjusts an emission position of the measurement light S with respect to the workpiece 60. A robot 50 changes a posture of the laser head 30 with respect to the workpiece 60. A control unit 55 controls operation of the adjustment mechanism 40 on the basis of a degree of inclination of the posture of the laser head 30 obtained in advance.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a laser welding apparatus configured to irradiate a welding portion with a coaxial laser beam and a measurement beam, and to measure the penetration depth of the welding portion based on the measurement beam reflected by the welding portion.

[0003] The laser beam and the measurement beam are combined into a coaxial light beam by a beam splitter. The laser head is provided with an adjustment mechanism (irradiation position switching unit). The adjustment mechanism adjusts the incident position of the measurement beam with respect to the beam splitter by moving a holder holding an optical fiber in the vertical and horizontal directions, for example, with a first cam and a second cam.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, the inventor of the present application newly found that when performing laser welding on a welding portion with the laser head tilted, depending on the tilt posture of the laser head, the emission position of the measurement beam may deviate from the emission position of the laser beam.

[0006] Specifically, depending on the tilt posture of the laser head, the direction of the self-weight of the adjustment mechanism mounted on the laser head changes, and the deflection direction of the adjustment mechanism changes. As a result, there is a possibility that a positional deviation between the laser beam and the measurement beam corresponding to the deflection generated in the adjustment mechanism may occur as compared with the case where the laser head is not tilted.

[0007] The present invention has been made in view of such a point, and an object thereof is to suppress a shift in the emission position of measurement light with respect to the emission position of laser light when the posture of the laser head is changed.

Means for Solving the Problems

[0008] A first invention is a laser welding apparatus that emits laser light to a workpiece to perform laser welding, the laser head that emits the laser light and measurement light having a different wavelength from the laser light to the workpiece, an optical interferometer that receives the measurement light reflected by the workpiece and measures the penetration depth of the workpiece, an adjustment mechanism that adjusts the emission position of the measurement light with respect to the workpiece, a robot that changes the posture of the laser head with respect to the workpiece, and a control unit that controls the operation of the adjustment mechanism based on the inclination degree of the posture of the laser head obtained in advance.

[0009] In the first invention, the emission position of the measurement light with respect to the workpiece is adjusted based on the posture of the laser head.

[0010] Specifically, when the laser head is tilted, the emission position of the measurement light with respect to the workpiece changes in response to the deflection caused by the change in the self-weight direction of the adjustment mechanism. Note that the direction and amount of the position shift of the measurement light corresponding to the tilted posture of the laser head can be measured in advance by a measurement test or the like performed before laser welding.

[0011] Then, based on the posture of the laser head during laser welding, the emission position of the measurement light is changed so as to correct the position shift of the measurement light caused by tilting the laser head.

[0012] Thereby, when the posture of the laser head is changed, it is possible to suppress a shift in the emission position of the measurement light with respect to the emission position of the laser light.

[0013] The second invention is the laser welding apparatus of the first invention, wherein the control unit controls the operation of the adjustment mechanism such that the emission position of the measurement light is located within a predetermined allowable region including the emission position of the laser light.

[0014] In the second invention, the emission position of the measurement light is changed so that the measurement light is positioned within a predetermined allowable region including the emission position of the laser light.

[0015] Thereby, the emission position of the measurement light displaced due to the inclination posture of the laser head can be moved close to the emission position of the laser light, and the penetration depth of the workpiece can be accurately measured.

[0016] The third invention is the laser welding apparatus of the second invention, wherein the allowable region is a circular region with a radius D centered on the emission position of the laser light, and the control unit controls the operation of the adjustment mechanism such that when the distance d between the emission position of the laser light and the emission position of the measurement light satisfies D < d, D ≥ d.

[0017] In the third invention, due to the inclination posture of the laser head, the emission position of the measurement light displaced outside the allowable region can be moved inside the allowable region, and the penetration depth of the workpiece can be accurately measured.

[0018] The fourth invention is the laser welding apparatus according to any one of the first to third inventions, wherein the control unit controls the operation of the adjustment mechanism such that when the posture of the laser head is a vertical posture in which the optical axis of the laser light extends in the vertical direction, the emission position of the laser light and the emission position of the measurement light are at the same position.

[0019] In the fourth invention, when the laser head is in a vertical posture, the emission position of the laser light and the emission position of the measurement light are at the same position.

[0020] In this way, based on the case where the laser head is in a vertical posture, it is possible to calculate the displacement direction and displacement amount of the measurement light when the laser head is tilted. As a result, it is possible to suppress the complexity of the calculation of the correction amount for correcting the displacement of the measurement light.

[0021] A fifth invention is a laser welding method for performing laser welding by emitting a laser beam onto a workpiece, comprising: a laser head that emits the laser beam and measurement light having a wavelength different from that of the laser beam onto the workpiece; a step of changing the posture of the laser head with respect to the workpiece; a step of adjusting the emission position of the measurement light with respect to the workpiece based on a previously obtained degree of inclination of the posture of the laser head; and a step of receiving the measurement light reflected by the workpiece and measuring the penetration depth of the workpiece.

[0022] In the fifth invention, based on the posture of the laser head during laser welding, the emission position of the measurement light is changed so as to correct the displacement of the measurement light caused by tilting the laser head.

[0023] Thereby, when the posture of the laser head is changed, it is possible to suppress the displacement of the emission position of the measurement light with respect to the emission position of the laser beam.

Advantages of the Invention

[0024] According to the present invention, when the posture of the laser head is changed, it is possible to suppress the displacement of the emission position of the measurement light with respect to the emission position of the laser beam.

Brief Description of the Drawings

[0025]

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Mode for Carrying Out the Invention

[0026] Hereinafter, embodiments of the present invention 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 invention, its applications, or its uses.

[0027] As shown in FIG. 1, the laser welding apparatus 1 includes a laser oscillator 10, a first transmission fiber 11, a second transmission fiber 12, an optical interferometer 20, a laser head 30, an automatic stage 40 as an adjustment mechanism, a robot 50, and a control unit 55.

[0028] The laser oscillator 10 outputs a laser beam L. The laser oscillator 10 is connected to the laser head 30 by the first transmission fiber 11. The laser beam L is transmitted from the laser oscillator 10 to the laser head 30 via the first transmission fiber 11.

[0029] The optical interferometer 20 uses the technology of Swept Source Optical Coherence Tomography (SS-OCT: wavelength-scanning optical coherence tomography) to receive the measurement light S reflected by the workpiece 60 and measures the penetration depth of the welded portion 65 of the workpiece 60. The optical interferometer 20 includes a measurement light oscillator 21 and a measurement unit 22.

[0030] The measurement light oscillator 21 outputs measurement light S having a wavelength different from that of the laser light L. Note that the wavelength difference between the laser light L and the measurement light S is preferably 100 nm or more. The measurement unit 22 measures the penetration depth of the welded portion 65.

[0031] The optical interferometer 20 and the laser head 30 are connected by the second transmission fiber 12. The measurement light S is transmitted from the optical interferometer 20 to the laser head 30 via the second transmission fiber 12.

[0032] The workpiece 60 includes an upper plate 61 and a lower plate 62. The upper plate 61 is overlapped on the upper surface of the lower plate 62. The laser welding apparatus 1 welds the upper plate 61 and the lower plate 62 by emitting the laser light L onto the upper surface of the upper plate 61.

[0033] The laser head 30 emits the laser light L and the measurement light S toward the workpiece 60. The laser head 30 includes a first collimating lens 31, a second collimating lens 32, a dichroic mirror 33, and a condenser lens 34.

[0034] The first collimating lens 31 collimates the laser light L emitted from the emission end of the first transmission fiber 11. The second collimating lens 32 collimates the measurement light S emitted from the emission end of the second transmission fiber 12.

[0035] The dichroic mirror 33 transmits the laser light L and reflects the measurement light S. The dichroic mirror 33 superposes the laser light L and the measurement light S coaxially and guides them to the condenser lens 34.

[0036] The condensing lens 34 condenses the laser beam L and the measurement light S. The laser beam L and the measurement light S condensed by the condensing lens 34 are emitted to the workpiece 60.

[0037] Note that the condensing lens 34 also has a function of causing the measurement light S reflected from the welding portion 65 of the workpiece 60 to enter the optical interferometer 20 again via the dichroic mirror 33.

[0038] The automatic stage 40 is mounted on the side of the laser head 30. The automatic stage 40 is disposed on the incident side of the second collimating lens 32. The output end of the second transmission fiber 12 is connected to the automatic stage 40. The automatic stage 40 has an X-axis table 41 and a Y-axis table 42 (see also FIG. 2, which is a side view of the automatic stage as viewed from the axial direction of the second transmission fiber 12 toward the laser head 30 side of FIG. 1).

[0039] The automatic stage 40 drives the X-axis table 41 and the Y-axis table 42. The automatic stage 40 adjusts the incident position of the measurement light S with respect to the second collimating lens 32 by moving the output end of the second transmission fiber 12 in the X-axis direction and the Y-axis direction.

[0040] Thereby, the emission position of the measurement light S emitted from the laser head 30 with respect to the workpiece 60 is adjusted. That is, the emission position of the measurement light S with respect to the emission position of the laser beam L can be changed.

[0041] The robot 50 has a robot arm 51. The laser head 30 is attached to the tip of the robot arm 51. The robot arm 51 has a plurality of joint portions 52.

[0042] The robot 50 moves the laser head 30 along a predetermined welding direction and changes the position and posture of the laser head 30 with respect to the workpiece 60. Thereby, the emission positions of the laser beam L and the measurement light S with respect to the workpiece 60 are moved, and laser welding is performed.

[0043] The control unit 55 is composed of, for example, an electronic computer. The control unit 55 has a storage unit 56. Various data related to welding conditions are stored in the storage unit 56.

[0044] The control unit 55 is connected to the laser oscillator 10, the optical interferometer 20, the laser head 30, the automatic stage 40, and the robot 50. The control unit 55 controls the operations of the laser oscillator 10, the optical interferometer 20, the laser head 30, the automatic stage 40, and the robot 50. The control unit 55 also has a function of controlling, in addition to the moving speed of the laser head 30, the start and stop of the output of the laser beam L and the output intensity of the laser beam L.

[0045] In the laser welding apparatus 1, when welding the welded portion 65 of the workpiece 60 having the upper plate 61 and the lower plate 62, the laser beam L is emitted onto the upper surface of the upper plate 61 from above the workpiece 60.

[0046] The welded portion 65 where the laser beam L is emitted melts from its upper part to form a molten pool. When the welded portion 65 melts, the molten metal evaporates from the molten pool, and the keyhole 66 is formed by the pressure of the vapor generated during evaporation. Here, the molten pool and the keyhole 66 are collectively treated as the welded portion 65. Behind the molten pool in the welding direction, a weld bead is formed by the solidification of the molten pool.

[0047] At this time, the measurement light S emitted from the optical interferometer 20 is superposed coaxially with the laser beam L emitted from the laser oscillator 10 by the dichroic mirror 33. The laser beam L and the measurement light S are emitted into the keyhole 66. The emitted measurement light S is reflected at the bottom of the keyhole 66 and enters the optical interferometer 20 through the dichroic mirror 33.

[0048] The optical path length of the measurement light S incident on the optical interferometer 20 is measured by the measurement unit 22. The measurement unit 22 specifies the depth of the keyhole 66 as the penetration depth of the welded portion 65 based on the measured optical path length. In the laser welding apparatus 1, the quality of the welded portion 65 is determined based on the specified penetration depth.

[0049] As described above, in the laser welding apparatus 1 according to the present embodiment, it is possible to measure the penetration depth of the welded portion 65 simultaneously with the laser welding.

[0050] <Regarding the displacement of the measurement light> By the way, when performing laser welding on the welded portion 65 with the laser head 30 in an inclined posture, depending on the inclined posture of the laser head 30, there is a possibility that the emission position of the measurement light S may be displaced with respect to the emission position of the laser light L.

[0051] Specifically, depending on the inclined posture of the laser head 30, the self-weight direction of the automatic stage 40 mounted on the laser head 30 changes, and the deflection direction of the automatic stage 40 changes. As a result, compared with the case where the laser head 30 is not inclined, there is a possibility that a displacement occurs between the laser light L and the measurement light S corresponding to the deflection generated in the automatic stage 40.

[0052] Therefore, in the present embodiment, when the posture of the laser head 30 is changed, it is possible to suppress the displacement of the emission position of the measurement light S with respect to the emission position of the laser light L.

[0053] Specifically, as shown in FIG. 3, the case where the posture of the laser head 30 is a vertical posture in which the optical axis of the laser light L extends in the vertical direction is used as a reference for the tilt angle V of the laser head 30. The tilt angle of the laser head 30 at this time is V = 0°.

[0054] And, when viewed from the direction in which the laser head 30 is disposed on the front side of the paper surface of FIG. 3 and the automatic stage 40 is disposed on the back side of the paper surface of FIG. 3, the direction in which the laser head 30 tilts in the clockwise direction is defined as the plus direction. In the example shown by the phantom line in FIG. 3, the posture in which the laser head 30 is tilted in the plus direction so that V = 45° is shown.

[0055] Next, as shown in FIG. 4, in a plan view, the attitude of the laser head 30 with the laser head 30 disposed on the left side and the automatic stage 40 disposed on the right side is taken as the reference for the twist angle W which is the tilt angle of the laser head 30. At this time, the twist angle of the laser head 30 is W = 0°.

[0056] And the direction in which the laser head 30 tilts in the clockwise direction in FIG. 4 is taken as the plus direction. Also, the direction in which the laser head 30 tilts in the counterclockwise direction in FIG. 4 is taken as the minus direction. In the example shown by the phantom line in FIG. 4, the attitude in which the laser head 30 is tilted in the plus direction to W = 45° is shown.

[0057] When the attitude of the laser head 30 is the vertical attitude in which the optical axis of the laser beam L extends in the vertical direction, the control unit 55 controls the operation of the automatic stage 40 so that the emission position of the laser beam L and the emission position of the measurement light S are at the same position. That is, when the tilt angle of the laser head 30 is V = 0°, the laser beam L and the measurement light S are coaxially overlapped (see FIG. 7).

[0058] When the laser head 30 is tilted, the emission position of the measurement light S with respect to the work 60 changes according to the deflection caused by the change in the self-weight direction of the automatic stage 40. In the example shown in FIG. 5, in the XY coordinate system, the emission position of the measurement light S is shifted diagonally upward to the right with respect to the emission position of the laser beam L.

[0059] Here, the allowable region 70 shown by the phantom line in FIG. 5 is a circular region with a radius D centered on the emission position of the laser beam L, in other words, it is the allowable region for the displacement of the measurement light S with respect to the emission position of the laser beam L. In the example shown in FIG. 5, the distance d between the emission position of the laser beam L and the emission position of the measurement light S is such that D < d.

[0060] Thus, when the emission position of the measurement light S is displaced outside the predetermined allowable region 70 including the emission position of the laser beam L, there is a risk of erroneously detecting the penetration depth of the welded portion 65.

[0061] Therefore, in the present embodiment, the positional deviation of the emission position of the measurement light S based on the posture of the laser head 30 is suppressed.

[0062] Specifically, the positional deviation direction and amount of the measurement light S corresponding to the tilt posture of the laser head 30, that is, the tilt angle V and twist angle W of the laser head 30, can be measured in advance by a measurement test or the like performed before laser welding.

[0063] When conducting the measurement test, for example, with a beam profiler (not shown) arranged at the focal position of the laser head 30, the beam profiler is fixed to the laser head 30. Then, while changing the posture of the laser head 30, that is, while varying the tilt angle V and twist angle W of the laser head 30, a table showing the positional relationship between the laser light L and the measurement light S obtained by the beam profiler is created and stored in the storage unit 56.

[0064] FIG. 6 is an example of a table that aggregates data showing changes in the beam profiler coordinates (x, y) when the tilt angle V and twist angle W of the laser head 30 are varied. By referring to this table, based on the tilt angle V and twist angle W of the laser head 30, that is, the degree of inclination of the posture of the laser head 30 obtained in advance, the positional deviation direction and amount of the emission position of the measurement light S with respect to the emission position of the laser light L can be calculated.

[0065] And in order to correct the positional deviation of the emission position of the measurement light S with respect to the emission position of the laser light L, the operation of the automatic stage 40 may be controlled so as to change the emission position of the measurement light S in the direction opposite to the positional deviation direction and amount calculated from the table.

[0066] Specifically, a beam profiler that measures the beam diameter and spatial intensity distribution of the laser beam L creates a correction table containing data with the positive and negative values of a table obtained by measuring the emission position of the laser beam L, the emission position of the measurement light S, etc. reversed, and stores it in the storage unit 56. Then, based on the tilt angle V and twist angle W of the laser head 30, a correction amount for eliminating the positional deviation of the measurement light S may be calculated from the correction table.

[0067] For the correction amount in an arbitrary posture not stored in the correction table, interpolation values of the actually measured tilt angle V and twist angle W may be used.

[0068] Hereinafter, a procedure for correcting the positional deviation of the emission position of the measurement light S with respect to the emission position of the laser beam L will be described.

[0069] As shown in FIG. 7, first, before starting laser welding, by setting the tilt angle of the laser head 30 to V = 0°, the laser beam L and the measurement light S are coaxially overlapped. In the example shown in FIG. 7, the emission position of the laser beam L and the emission position of the measurement light S both coincide with the reference position P0.

[0070] Next, at the welding start position, the posture of the laser head 30 is changed based on the welding program. For example, the posture of the laser head 30 is changed so that the tilt angle of the laser head 30 becomes V = v1. For example, let v1 = 10°. The twist angle W is omitted for easier explanation.

[0071] Here, the emission position of the measurement light S becomes a position shifted from the reference position P0 to the position P1. In the example shown in FIG. 7, the position P1 is a position shifted diagonally upward to the right from the reference position P0 which is the emission position of the laser beam L.

[0072] Then, based on the tilt angle V and twist angle W of the laser head 30, a correction amount (xv1, yv1) for correcting the positional deviation of the measurement light S is calculated based on the correction table.

[0073] The control unit 55 controls the operation of the automatic stage 40 so that the emission position of the measurement light S is located within a predetermined allowable region 70 including the emission position P0 of the laser light L.

[0074] Specifically, the allowable region 70 is a circular region with a radius D centered on the emission position P0 of the laser light L. When the distance d between the emission position P0 of the laser light L and the emission position P1 of the measurement light S satisfies D < d, the control unit 55 controls the operation of the automatic stage 40 so that D ≥ d.

[0075] When the emission position of the measurement light S is located inside the allowable region 70, it can be determined that the amount of positional deviation is slight enough not to affect the measurement of the penetration depth of the welding part 65, and the correction operation of the measurement light S may not be performed.

[0076] In the example shown in FIG. 7, based on the correction amount (xv1, yv1) when the tilt angle of the laser head 30 is V = v1, the emission position of the measurement light S is corrected so as to move from the position P1 to the position P1c. The position P1c is located inside the allowable region 70.

[0077] Thereby, when the attitude of the laser head 30 is changed, it is possible to suppress the deviation of the emission position of the measurement light S with respect to the emission position of the laser light L. Further, due to the inclined attitude of the laser head 30, the emission position P1 of the measurement light S that has deviated outside the allowable region 70 is moved to the emission position P1c inside the allowable region 70, and the penetration depth of the workpiece 60 can be accurately measured.

[0078] As shown in FIG. 8, after the laser welding is completed, the emission position of the measurement light S is returned to the position before correction. Specifically, when the tilt angle of the laser head 30 is V = v1, the emission position of the measurement light S at the end of welding is the position P1c. The control unit 55 controls the operation of the automatic stage 40 so that the emission position of the measurement light S becomes the position P1 before correction. In this state, by setting the tilt angle of the laser head 30 to V = 0°, the laser light L and the measurement light S can be coaxially overlapped.

[0079] Thereafter, at the next welding start position, based on the welding program, the attitude of the laser head 30 is changed. For example, the attitude of the laser head 30 is changed so that the tilt angle V of the laser head 30 becomes V = v2. For example, let v2 = 20°. Note that the twist angle W is omitted for clarity of explanation.

[0080] Here, the emission position of the measurement light S is shifted from the position P1 to the position P2. In the example shown in FIG. 8, the position P2 is shifted diagonally upward to the left from the reference position P0 which is the emission position of the laser light L.

[0081] Then, based on the tilt angle V and the twist angle W of the laser head 30, a correction amount (xv2, yv2) for correcting the positional deviation of the measurement light S is calculated based on a correction table.

[0082] The control unit 55 controls the operation of the automatic stage 40 so that the emission position of the measurement light S is located within a predetermined allowable region 70 including the emission position P0 of the laser light L. In the example shown in FIG. 8, based on the correction amount (xv2, yv2) when the tilt angle of the laser head 30 is V = v2, the emission position of the measurement light S is corrected to move from the position P2 to the position P2c. The position P2c is located inside the allowable region 70.

[0083] Thereby, when the attitude of the laser head 30 is changed, it is possible to suppress the deviation of the emission position of the measurement light S with respect to the emission position of the laser light L.

[0084] Hereinafter, after the laser welding is completed and before the laser welding is performed at the next welding start position, the reason for returning the emission position of the measurement light S to the position before correction will be described using a comparative example.

[0085] As shown in FIG. 9, when the tilt angle of the laser head 30 is V = v1 at the end of the laser welding and the emission position of the measurement light S after correction (position P1c) is not returned to the position before correction (position P1), the emission position of the measurement light S remains at the position P1c.

[0086] After that, at the next welding start position, for example, when the tilt angle of the laser head 30 is changed so that V = v2, the emission position of the measurement light S becomes a position shifted from the position P1c to the position P2'.

[0087] Note that the direction and amount of displacement from the position P1c to the position P2' are the same as the direction and amount of displacement from the position P1 to the position P2 described in FIG. 8 (see the two-dot chain line from the position P1 to the position P2 in FIG. 9).

[0088] Then, based on the correction amounts (xv2, yv2) when the tilt angle of the laser head 30 is V = v2, correction is performed so that the emission position of the measurement light S moves from the position P2' to the position P2c'. Here, the direction and amount of displacement from the position P2' to the position P2c' are the same as the direction and amount of displacement from the position P2 to the position P2c described in FIG. 8 (see the two-dot chain line from the position P2 to the position P2c in FIG. 9).

[0089] However, since the data in the correction table is created based on the direction and amount of displacement from the reference position P0 which is the emission position of the laser beam L, in the example shown in FIG. 9, even when the correction amounts (xv2, yv2) are used as they are, the corrected position P2c' will be located outside the allowable region 70. Therefore, it is necessary to correct the emission position of the measurement light S in the direction indicated by the dashed arrow so as to move from the position P2' to the position P2c.

[0090] In this case, it is necessary to calculate a new correction amount considering the correction amount (xv1, yv1) when the tilt angle of the laser head 30 is V = v1 and the correction amount (xv2, yv2) when the tilt angle of the laser head 30 is V = v2.

[0091] Also, the position P2' of the measurement light S is often far from the reference position P0 of the laser beam L. In that case, since it is greatly affected by the hysteresis of the automatic stage 40, the position after correction by the calculated correction amount may be away from the reference position P0 of the laser beam L.

[0092] On the other hand, in this embodiment, after the laser welding is completed, the emission position of the measurement light S is returned to the position before correction, thereby suppressing the complication of the calculation of the correction amount for correcting the displacement of the measurement light S.

[0093] FIG. 10 is a graph showing the relationship between the twist angle W and the displacement amount. In the example shown in FIG. 10, the tilt angle of the laser head 30 is set to V = 78.75°. Further, a range of D = 0.003 mm is defined as the allowable region 70, and the displacement of the measurement light S is corrected in a range where the displacement amount exceeds D (d > D). Note that in a range where d < D, the displacement of the emission position of the measurement light S with respect to the emission position of the laser light L is not corrected.

[0094] In the example shown in FIG. 10, by correcting the displacement of the measurement light S according to the twist angle W of the laser head 30 so that d < D, it can be seen that in this range, the emission position of the measurement light S is located within the allowable region 70 regardless of the twist angle W.

Industrial Applicability

[0095] As described above, the present invention can suppress the displacement of the emission position of the measurement light with respect to the emission position of the laser light when the attitude of the laser head is changed, and thus has a very high practical effect and high industrial applicability.

Explanation of Reference Numerals

[0096] 1 Laser welding apparatus 20 Interferometer 30 Laser head 40 Automatic stage (adjustment mechanism) 50 Robot 55 Control unit 60 Workpiece 70 Allowable region L Laser light S Measurement light

Claims

1. A laser welding device that performs laser welding by emitting a laser beam to a workpiece, a laser head that emits the laser light and a measurement light having a different wavelength from the laser light to the workpiece; an optical interferometer that receives the measurement light reflected by the workpiece and measures the penetration depth of the workpiece; an adjustment mechanism for adjusting an emission position of the measurement light with respect to the workpiece; a robot that changes the attitude of the laser head with respect to the workpiece; a control unit that controls the operation of the adjustment mechanism based on a previously determined degree of inclination of the attitude of the laser head. Laser welding equipment.

2. 2. The laser welding apparatus according to claim 1, The control unit controls the operation of the adjustment mechanism so that the emission position of the measurement light is located within a predetermined allowable range including the emission position of the laser light. Laser welding equipment.

3. 3. The laser welding apparatus according to claim 2, the allowable region is a circular region having a radius D centered on the emission position of the laser light, The control unit controls the operation of the adjustment mechanism so that, when a distance d between the emission position of the laser light and the emission position of the measurement light is D<d, D≧d is satisfied. Laser welding equipment.

4. In the laser welding apparatus according to any one of claims 1 to 3, The control unit controls the operation of the adjustment mechanism so that an emission position of the laser light and an emission position of the measurement light are the same position when the laser head is in a vertical position in which the optical axis of the laser light extends in a vertical direction. Laser welding equipment.

5. A laser welding method for performing laser welding by emitting a laser beam to a workpiece, comprising: A laser head is provided which emits the laser light and a measurement light having a different wavelength from the laser light to the workpiece, changing the attitude of the laser head with respect to the workpiece; adjusting an emission position of the measurement light with respect to the workpiece based on a previously obtained degree of inclination of the attitude of the laser head; receiving the measurement light reflected by the workpiece and measuring the penetration depth of the workpiece; Laser welding method.

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