Laser processing apparatus and laser processing method

Abstract

To provide a laser beam machining apparatus and a laser beam machining method capable of accurately measuring the depth of a keyhole.SOLUTION: The laser processing apparatus sets a processing section passing through a target position on a processing surface, sets a measurement section centered on the target position in the processing section, and sets a plurality of data acquisition positions that are trajectories perpendicular to a processing direction in the measurement section. Further, the laser machining device acquires measurement data indicating the shape of the keyhole at each data acquisition position during the machining of the machining section, and creates projection data in which the measurement data is projected and superimposed in the machining direction. Then, the laser processing device obtains the second instruction value in the direction perpendicular to the processing direction at the target position based on the projection data. Accordingly, it is possible to provide a laser processing device and a laser processing method capable of accurately measuring the depth of the keyhole.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a laser processing apparatus and a laser processing method. [Background technology]

[0002] Patent Document 1 discloses a laser processing device that uses OCT (Optical Coherence Tomography) technology, which visualizes the internal structure of a sample using an optical coherence tomography (OCT), to measure the depth of a keyhole that is generated during metal processing using a laser beam.

[0003] The laser processing device of Patent Document 1 will be described below with reference to Fig. 26. Fig. 26 is a diagram schematically showing the configuration of the laser processing device disclosed in Patent Document 1.

[0004] 26, a processing laser beam 107 and a measuring beam 105 are introduced into a welding head 108. The measuring beam 105 passes through a collimator module 106 and a dichroic mirror 110, and is coaxially configured with the processing laser beam 107, sharing the same optical axis.

[0005] The measuring instrument is composed of an OCT optical system using an optical coherence tomography system, which is composed of an analysis unit 100, an optical fiber 101, a beam splitter 103, an optical fiber 104, a reference arm 102, and a measurement arm 109. Measurement light 105 is irradiated through the optical fiber 104 as measurement light of the OCT optical system.

[0006] The processing laser beam 107 and the measuring beam 105 are focused by a focusing lens 111 and irradiated onto a workpiece 112. The workpiece 112 is processed by the processing laser beam 107. That is, when the focused processing laser beam 107 is irradiated onto a processing portion 113 of the workpiece 112, the metal constituting the workpiece 112 melts. As a result, a keyhole is formed by the pressure generated when the molten metal evaporates. Then, the measuring beam 105 is irradiated onto the bottom surface of the keyhole.

[0007] At this time, an interference signal is generated according to the optical path difference between the measurement light 105 (reflected light) reflected by the keyhole and the light (reference light) on the reference arm 102 side. This makes it possible to determine the depth of the keyhole from the interference signal. Immediately after the keyhole is formed, it is filled with the surrounding molten metal. Therefore, the depth of the keyhole is approximately the same as the depth of the molten part of the metal processing part (hereinafter referred to as "penetration depth"). This makes it possible to measure the penetration depth of the processing part 113. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Publication No. 2018-501964 Summary of the Invention [Problem to be solved by the invention]

[0009] In recent years, laser processing equipment that combines a galvanometer mirror and an fθ lens has become known. The galvanometer mirror is a mirror that can precisely control the direction in which the laser light is reflected. The fθ lens is a lens that focuses the laser light onto the processing point on the surface of the workpiece.

[0010] Therefore, it is conceivable to apply the method for measuring the keyhole depth disclosed in Patent Document 1 to a laser processing device that combines a galvanometer mirror and an fθ lens. In this case, however, the following problem occurs. Specifically, because the processing laser light and the measurement light have different wavelengths, chromatic aberration occurs in the fθ lens. This causes a deviation in the irradiation position of the processing laser light and the measurement light on the surface of the workpiece. As a result, there is a risk that the keyhole depth cannot be accurately measured using the measurement light.

[0011] The present disclosure provides a laser processing apparatus and a laser processing method that can accurately measure the depth of a keyhole. [Means for solving the problem]

[0012] A laser processing apparatus according to one embodiment of the present disclosure includes a laser oscillator that oscillates a processing laser beam that is irradiated at a processing point on a processing surface of a workpiece, and an optical interferometer that emits measurement beams that are irradiated at the processing point and generates an optical interference signal based on interference caused by an optical path difference between the measurement beam and a reference beam reflected at the processing point. The laser processing apparatus also includes a first mirror that changes the propagation direction of the processing laser beam and the measurement beam, a second mirror that changes the incident angle of the measurement beam on the first mirror, and a lens that focuses the processing laser beam and the measurement beam at the processing point. The laser processing apparatus also includes a control unit that controls the laser oscillator, the first mirror, and the second mirror based on corrected processing data, and a measurement processing unit that measures the depth of a keyhole created at the processing point by irradiating the processing laser beam based on the optical interference signal. The corrected processing data is data for eliminating deviations in the arrival positions on the processing surface of at least one of the processing laser beam and the measurement beam caused by chromatic aberration of the lens, and includes an output instruction value indicating the oscillation intensity of the processing laser beam, a first instruction value indicating the amount of movement of the first mirror, and a second instruction value indicating the amount of movement of the second mirror, all of which are set for each processing point. The control unit sets a processing section passing through a target position on the processing surface, sets a measurement section within the processing section centered on the target position, and sets multiple data acquisition positions within the measurement section as trajectories perpendicular to the processing direction. Furthermore, the control unit acquires measurement data indicating the shape of the keyhole at each data acquisition position during processing in the processing section, projects the measurement data in the processing direction to create superimposed projection data, and calculates a second instruction value in a direction perpendicular to the processing direction at the target position based on the projection data.

[0013] A laser processing method according to one embodiment of the present disclosure includes a first mirror that changes the propagation direction of a processing laser beam and a measurement beam, a second mirror that changes the angle of incidence of the measurement beam on the first mirror, and a lens that focuses the processing laser beam and the measurement beam at a processing point on a processing surface of a workpiece. The laser processing method is performed by a laser processing device that controls the first and second mirrors based on corrected processing data to irradiate the processing laser beam and the measurement beam onto the workpiece, and measures the depth of a keyhole created at the processing point by the irradiation of the processing laser beam based on interference caused by the optical path difference between the measurement beam reflected at the processing point and a reference beam. The corrected processing data is data for eliminating deviations in the arrival positions of at least one of the processing laser beam and the measurement beam on the processing surface caused by lens chromatic aberration. The data includes an output instruction value indicating the oscillation intensity of the processing laser beam, a first instruction value indicating the amount of movement of the first mirror, and a second instruction value indicating the amount of movement of the second mirror, all of which are preset for each processing point. The laser processing device then sets a processing section that passes through a target position on the processing surface, sets a measurement section within the processing section with the target position as its center, and sets a plurality of data acquisition positions within the measurement section that are trajectories perpendicular to the processing direction.Furthermore, the laser processing device acquires measurement data that indicates the shape of the keyhole at each of the data acquisition positions during processing of the processing section, projects the measurement data in the processing direction to create superimposed projection data, and calculates a second indication value in a direction perpendicular to the processing direction at the target position based on the projection data. [Effects of the Invention]

[0014] According to the present disclosure, it is possible to provide a laser processing apparatus and a laser processing method that can accurately measure the depth of a keyhole. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram schematically illustrating a configuration of a laser processing apparatus according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a diagram schematically showing the laser processing apparatus in a state in which the first mirror is moved from the origin position. [Figure 3] FIG. 3 is a diagram schematically illustrating the laser processing device in a state in which deviations in the arrival positions of the processing laser beam and the measurement beam due to chromatic aberration of magnification have been corrected. [Figure 4] FIG. 4 is a diagram schematically showing the trajectories of the processing laser light and the measurement light on the processing surface when the surface of the workpiece is scanned in a grid pattern by operating only the first mirror. [Figure 5] FIG. 5 is a flowchart showing a method for calculating a correction angle at a predetermined processing beam lattice point. [Figure 6] FIG. 6 is a diagram showing an example of a processing section and a data acquisition section that are set when the y-axis is selected as the axis of the correction angle to be obtained. [Figure 7] FIG. 7 is a diagram schematically showing the relationship between the processing point during processing and the data acquisition position. [Figure 8] FIG. 8 is a graph showing an example of the measurement results of the keyhole shape in the x direction when the processing direction is the +x direction. [Figure 9] FIG. 9 is a graph showing an example of the measurement results of the keyhole shape in the x direction when the processing direction is the −x direction. [Figure 10] FIG. 10 is a graph showing an example of the measurement results of the keyhole shape in the y direction when the processing direction is the +x direction. [Figure 11] FIG. 11 is a graph showing an example of the measurement results of the keyhole shape in the y direction when the processing direction is the −x direction. [Figure 12] FIG. 12 is a graph illustrating an example of overlapping a plurality of measurement data. [Figure 13] FIG. 13 is a graph illustrating an example of determining the correction angle from the projection data. [Figure 14] FIG. 14 is a diagram schematically showing cross-shaped processing marks that intersect at processing light lattice points. [Figure 15] FIG. 15 is a flowchart showing a method for creating the correction number table data. [Figure 16]FIG. 16 is a diagram schematically showing an example in which cross-shaped processing marks are formed at all processing light lattice points. [Figure 17] FIG. 17 is a diagram showing an example of the configuration of corrected processed data. [Figure 18] FIG. 18 is a flowchart showing a method for creating processed data. [Figure 19] FIG. 19 is a diagram showing a correction number table that schematically shows the configuration of correction number table data. [Figure 20] FIG. 20 is a flowchart showing a method for setting the correction angle. [Figure 21] FIG. 21 is a diagram showing the relationship between the scan angle X and the surrounding correction data points when the scan angle X set by the user does not match the scan angle for the correction number table of any data point on the correction number table. [Figure 22] FIG. 22 is a flowchart showing the laser processing method. [Figure 23] FIG. 23 is a flowchart showing a method for measuring the depth of a keyhole. [Figure 24] FIG. 24 is a diagram schematically showing the trajectories of the processing laser light and the measurement light on the processing surface in a state in which the influence of chromatic aberration of magnification has been corrected by the operation of the second mirror. [Figure 25] FIG. 25 is a diagram schematically showing the configuration of a laser processing device according to Modification 1 of the present disclosure. [Figure 26] FIG. 26 is a diagram schematically showing the laser processing device disclosed in Patent Document 1. As shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that common components in the drawings are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0017] (Embodiment) The laser processing apparatus according to the embodiment of the present disclosure will be described below in sections.

[0018] <Configuration of laser processing equipment> First, the configuration of a laser processing device 1 according to an embodiment of the present disclosure will be described with reference to FIG.

[0019] FIG. 1 is a diagram schematically showing the configuration of a laser processing device 1 according to the present embodiment.

[0020] As shown in FIG. 1, the laser processing device 1 of this embodiment includes a processing head 2, an optical interferometer 3, a measurement processing unit 4, a laser oscillator 5, a control unit 6, a first driver 7, a second driver 8, and the like.

[0021] The optical interferometer 3 emits measurement light 15 for OCT measurement. The emitted measurement light 15 is input to the processing head 2 from a measurement light introduction port 9 installed on a second mirror 17.

[0022] The laser oscillator 5 oscillates a processing laser beam 11 for laser processing. The oscillated processing laser beam 11 is input to the processing head 2 from a processing beam inlet 10.

[0023] The processing laser beam 11 input to the processing head 2 passes through the dichroic mirror 12 and is reflected by the first mirror 13. The reflected processing laser beam 11 passes through the lens 14 and is focused on a processing surface 19, which is the surface of the workpiece 18. As a result, a processing point 20 on the processing surface 19 of the workpiece 18 is laser-processed. At this time, the processing point 20 irradiated with the processing laser beam 11 melts, and a molten pool 21 is formed. Then, molten metal evaporates from the formed molten pool 21. As a result, a keyhole 22 is formed in the workpiece 18 by the pressure of the vapor generated when the molten metal evaporates.

[0024] Meanwhile, the measuring light 15 input to the processing head 2 is converted into parallel light by the collimating lens 16 and reflected by the second mirror 17. The measuring light 15 is then reflected by the dichroic mirror 12 and then reflected by the first mirror 13. The reflected measuring light 15 passes through the lens 14 and is focused at a processing point 20 on the processing surface 19 of the workpiece 18. The focused measuring light 15 is reflected by the bottom surface of the keyhole 22 and travels back along the above propagation path to the optical interferometer 3. At this time, the measuring light 15 optically interferes with a reference light (not shown) in the optical interferometer 3, generating an optical interference signal.

[0025] The measurement processing unit 4 measures the depth of the keyhole 22, i.e., the penetration depth of the processing point 20, from the optical interference signal generated by the optical interferometer 3. Here, the "penetration depth" means the distance between the apex of the melted part of the workpiece 18 and the processing surface 19.

[0026] Generally, the wavelength of the processing laser beam 11 is different from the wavelength of the measurement beam 15. Specifically, when, for example, a YAG laser or a fiber laser is used as the processing laser beam 11, the wavelength of the processing laser beam 11 is 1064 nm. On the other hand, when, for example, an OCT light source is used as the measurement beam 15, the wavelength of the measurement beam 15 is 1300 nm.

[0027] The dichroic mirror 12 has the property of transmitting light having the wavelength of the processing laser light 11 and reflecting light having the wavelength of the measurement light 15 .

[0028] The first mirror 13 and the second mirror 17 are movable mirrors that can rotate about two or more axes. The first mirror 13 and the second mirror 17 are, for example, galvanometer mirrors. The two axes correspond to, for example, the x-axis and y-axis shown in FIG. 1.

[0029] The first mirror 13 and the second mirror 17 are connected to the control unit 6 via a first driver 7 and a second driver 8, respectively, and operate under the control of the control unit 6. Specifically, the first driver 7 operates the first mirror 13 based on instructions from the control unit 6. The second driver 8 operates the second mirror 17 based on instructions from the control unit 6.

[0030] The control unit 6 includes a memory 31. The memory 31 stores processing data for performing desired processing on the workpiece 18, and correction data for performing correction, which will be described later.

[0031] 1 shows, as an example, only the rotational movement of each of first mirror 13 and second mirror 17 about the rotation axis in the y direction (see the dotted line and double-headed arrow in the figure). However, in reality, each of first mirror 13 and second mirror 17 is configured to be capable of rotational movement about two or more axes, as described above. Therefore, each of first mirror 13 and second mirror 17 is also capable of rotational movement about, for example, the rotation axis in the x direction (see arrow x in the figure).

[0032] For simplicity of explanation, the following description will be given assuming that first mirror 13 and second mirror 17 each only rotate about a rotation axis in the y direction (see arrow y in the drawing).

[0033] When the second mirror 17 is at the origin position, as shown in FIG. 1, the measurement optical axis 23 of the measurement light 15 coincides with the processing optical axis 24 of the processing laser light 11 after being reflected by the dichroic mirror 12.

[0034] Furthermore, when the first mirror 13 is at the origin position, as shown in FIG. 1, the processing optical axis 24 of the processing laser light 11 coincides with the lens optical axis 25, which is the center of the lens 14, when it passes through the lens 14 after being reflected by the first mirror 13.

[0035] In the following description, the position (corresponding to the irradiation position) where the processing laser beam 11 and the measurement beam 15, which have passed through the center of the lens 14, reach the processing surface 19 of the workpiece 18 will be referred to as the "processing origin 26" (see FIG. 2). In other words, the origin positions of the first mirror 13 and the second mirror 17 are the positions where the processing laser beam 11 and the measurement beam 15 pass through the center of the lens 14.

[0036] The lens 14 is a lens for focusing the processing laser light 11 and the measurement light 15 onto the processing point 20. The lens 14 is, for example, an fθ lens.

[0037] The first mirror 13 and the lens 14 constitute a typical optical scanning system consisting of a galvanometer mirror and an fθ lens. Therefore, the arrival position of the processing laser beam 11 on the processing surface 19 can be controlled by rotating the first mirror 13 by a predetermined angle from its origin position. Hereinafter, the angle by which the first mirror 13 is rotated from its origin position will be referred to as the "movement amount of the first mirror 13." Note that the movement amount of the first mirror 13 can be uniquely set once the positional relationship of each optical member constituting the processing head 2 and the distance from the lens 14 to the processing surface 19 are determined. This allows the processing laser beam 11 to be irradiated onto the desired processing point 20.

[0038] At this time, the distance from the lens 14 to the processing surface 19 is preferably set so that the focal position where the processing laser beam 11 is most focused coincides with the processing surface 19. This allows the workpiece 18 to be processed most efficiently with the processing laser beam 11. Note that the distance from the lens 14 to the processing surface 19 is not limited to this, and may be set to any appropriate distance depending on the purpose of processing.

[0039] The first mirror 13 changes its movement amount in accordance with a predetermined operation schedule, so that the processing laser beam 11 can be scanned and irradiated onto the processing surface 19 at any position of the processing point 20.

[0040] Furthermore, the control unit 6 controls the on / off switching of the laser oscillator 5. This allows laser processing of any position on the processing surface 19 within the range that can be scanned by the processing laser light 11, in any pattern.

[0041] <Effects of chromatic aberration> Next, the influence of chromatic aberration of the lens 14 will be described with reference to FIG. 2 is a diagram schematically showing the laser processing apparatus 1 in a state where the first mirror 13 has been moved from the origin position. In FIG. 2, it is assumed that the second mirror 17 is at the origin position.

[0042] 2, the processing laser beam 11 and the measurement beam 15 reflected by the first mirror 13 travel on the same optical axis until they reach the lens 14. However, after passing through the lens 14, a deviation occurs in the traveling direction of the processing laser beam 11 and the measurement beam 15. That is, as shown in FIG. 2, a processing optical axis 24a, which is the optical axis of the processing laser beam 11, and a measurement optical axis 23a, which is the optical axis of the measurement beam 15, are misaligned. Therefore, the measurement beam 15 reaches a position different from the processing point 20.

[0043] This is due to chromatic aberration of the lens 14. Chromatic aberration is an aberration that occurs because general optical materials, including the lens 14, have different refractive indices for different wavelengths of light.

[0044] There are two types of chromatic aberration: axial chromatic aberration and lateral chromatic aberration. Axial chromatic aberration is an aberration caused by the fact that the focal position of a lens varies depending on the wavelength of light. On the other hand, lateral chromatic aberration is an aberration caused by the fact that the image height on the focal plane (processing plane 19) varies depending on the wavelength of light. Note that the deviation in the traveling direction of the processing laser light 11 (processing optical axis 24a) and the measurement light 15 (measurement optical axis 23a) after passing through the lens 14, as shown in Figure 2, is caused by the above-mentioned lateral chromatic aberration.

[0045] At this time, axial chromatic aberration also occurs simultaneously in the laser processing apparatus 1 of this embodiment. However, the deviation between the processing laser beam 11 and the measurement beam 15 due to axial chromatic aberration can be dealt with by adjusting the distance between the collimator lens 16 and the measurement beam inlet 9. In other words, by using the collimator lens 16 to change the state of the measurement beam 15 immediately after transmission from a parallel beam to a slightly divergent or convergent state, it is possible to suppress the occurrence of axial chromatic aberration.

[0046] 2, the position where the measuring light 15 reaches the processing surface 19 is farther from the processing origin 26 than the position where the processing laser light 11 reaches the processing surface 19. However, the above positional relationship is just one example. That is, depending on the lens configuration of the lens 14 and the wavelength relationship between the processing laser light 11 and the measuring light 15, the measuring light 15 may reach a position closer to the processing origin 26 than the processing laser light 11. Generally, light with a longer wavelength reaches a position farther from the processing origin 26.

[0047] One method for correcting the lateral chromatic aberration is to impart the properties of an achromatic lens to the lens 14. However, if the lens 14 is to be endowed with the properties of both an fθ lens and an achromatic lens, highly advanced optical design technology is required. As a result, designing the lens 14 requires a great deal of time and cost.

[0048] Therefore, in the laser processing apparatus 1 of the present embodiment, the second mirror 17 is operated (moved) as described below, thereby realizing correction of chromatic aberration of magnification at low cost.

[0049] <How to correct lateral chromatic aberration> Next, a method for correcting the chromatic aberration of magnification of the lens 14 will be described with reference to FIG.

[0050] FIG. 3 is a diagram schematically showing the laser processing device 1 in a state in which deviations in the arrival positions of the processing laser beam 11 and the measuring beam 15 due to chromatic aberration of magnification have been corrected.

[0051] 3, the second mirror 17 is moved by a predetermined movement amount (movement angle) from the origin position. As a result, as shown in FIG. 3, the processing optical axis 24 of the processing laser beam 11 and the measurement optical axis 23 of the measurement beam 15 are no longer coaxial between the dichroic mirror 12 and the lens 14. However, after passing through the lens 14, the processing laser beam 11 and the measurement beam 15 each reach the same position on the processing surface 19, i.e., the processing point 20.

[0052] At this time, as shown in Fig. 3, the processing optical axis 24a of the processing laser beam 11 passes through the same position as the processing optical axis 24a shown in Fig. 2. On the other hand, the measurement optical axis 23b of the measurement beam 15 corrected by the operation of the second mirror 17 passes through a different position from the measurement optical axis 23a shown in Fig. 2.

[0053] The amount of movement of second mirror 17 (i.e., the angle by which second mirror 17 is rotated from its origin position) is associated one-to-one with the amount of movement of first mirror 13. In this case, the amount of movement of first mirror 13 is uniquely determined by the position of processing point 20. Therefore, the amount of movement of second mirror 17 is also uniquely determined by the position of processing point 20.

[0054] In the following, the amount of movement of the second mirror 17 is referred to as a "correction angle" (corresponding to a "second instruction value" to be described later), and how to obtain this correction angle will be described.

[0055] <Relationship between correction angle and scanning angle> Next, the relationship between the correction angle of the second mirror 17 and the scanning angle of the first mirror 13 will be described.

[0056] Here, the focal length of lens 14 is f, the angle of light incident on lens 14 from lens optical axis 25 is θ, and the distance from the optical axis on the image plane of the light ray transmitted through lens 14 (hereinafter referred to as "image height") is h. In this case, the relationship h=fθ holds for lens 14, which is an fθ lens.

[0057] As described above, the first mirror 13 has two axes about which it rotates.

[0058] Therefore, the two axes are assumed to be the x-axis and y-axis, the angle of the x-axis component of the light reflected by the first mirror 13 from the lens optical axis 25 is assumed to be θx, and the angle of the y-axis component from the lens optical axis 25 is assumed to be θy. If the image heights in the x and y directions on the image plane are assumed to be x and y, respectively, then the relationships x = fθx and y = fθy hold. Thus, if the position where the processing laser beam 11 reaches the processing surface 19 is assumed to be (x, y), then (x, y) = (fθx, fθy).

[0059] Furthermore, when light is incident on the mirror, the angle of emergence of reflected light from the mirror changes by twice the angle. Therefore, if the movement amount of first mirror 13 is (φx, φy), the relationship (2φx, 2φy) = (θx, θy) holds. In the following explanation, the movement amount (φx, φy) of first mirror 13 will be referred to as the "scan angle" (corresponding to the "first indication value" described later).

[0060] As described above, in the laser processing apparatus 1 of this embodiment, when the scanning angle (φx, φy) of the first mirror 13 is determined, the arrival position of the processing laser light 11 on the processing surface 19, i.e., the position (x, y) of the processing point 20, is also determined.

[0061] As described above, the scanning angle is uniquely determined by the position of the processing point 20. Similarly, the correction amount of the second mirror 17 is also uniquely determined by the position of the processing point 20.

[0062] Therefore, in this embodiment, the relationship between the scanning angle and the correction amount is calculated in advance for each position of a predetermined processing point 20. Then, during processing, the second mirror 17 is moved by the correction amount corresponding to the position of the processing point 20. This makes it possible to correct the deviation of the irradiation position of the measurement light 15 from the irradiation position of the processing laser light 11 due to the chromatic aberration of magnification of the lens 14 described above.

[0063] <Correction Table Data> Next, the correction table data will be explained.

[0064] The correction number table data is data indicating the correspondence between the scanning angle and the correction angle for each processing point 20 (an example of corrected processing data).

[0065] First, the trajectories of the processing laser beam 11 and the measuring beam 15 on the processing surface 19 of the workpiece 18 will be described with reference to FIG.

[0066] FIG. 4 is a diagram showing the trajectories of the processing laser light 11 and the measurement light 15 on the processing surface 19 of the workpiece 18 when the processing surface 19 is scanned in a grid pattern by operating only the first mirror 13 without operating the second mirror 17.

[0067] 4 shows the processing surface 19 as viewed from the lens 14 side. In FIG. 4, a processing light trajectory 28, which is the trajectory of the processing laser beam 11, is shown by a solid line, and a measurement light trajectory 27, which is the trajectory of the measurement beam 15, is shown by a dotted line.

[0068] The example shown in FIG. 4 shows the trajectories of the processing laser beam 11 and the measurement beam 15 when the second mirror 17 is not operated and therefore no correction for lateral chromatic aberration is performed. Therefore, the trajectories of the processing laser beam 11 and the measurement beam 15 coincide near the processing origin 26. However, due to lateral chromatic aberration, the deviation between the two trajectories increases as the beam moves away from the processing origin 26. In other words, the processing beam trajectory 28 traces a lattice-like pattern without distortion. On the other hand, the measurement beam trajectory 27 traces a distorted pincushion-shaped trajectory. Note that the shape of the measurement beam trajectory 27 shown in FIG. 4 is just an example. In other words, the distorted shape of the measurement beam trajectory 27 changes depending on the optical characteristics of the lens 14.

[0069] Similarly, the amount of deviation between the positions of the processing light locus 28 and the measurement light locus 27 also depends on the optical characteristics and optical design of the lens 14. As a general example, in the case of a commercially available fθ lens in which the focal length of the lens 14 is 250 mm and the diameter of the processing surface area is about 200 mm, the loci of the processing laser beam 11 and the measurement beam 15 deviate by 0.2 mm to 0.4 mm near the outermost periphery of the processing surface area.

[0070] In contrast, the diameter of the keyhole 22 (see FIG. 1, for example) created by irradiating the processing point 20 with the processing laser beam 11 is small, generally between 0.03 mm and 0.2 mm, although it depends on the power and spatial coherency of the processing laser beam and the focusing ability of the lens 14. Therefore, due to a misalignment between the processing laser beam 11 and the measuring beam 15 caused by chromatic aberration of the lens 14, the measuring beam 15 may not reach the bottom of the keyhole 22. This makes it impossible to accurately measure the penetration depth with the measuring beam 15.

[0071] Note that, while FIG. 4 illustrates an example of a grid pattern with 4×4 equally spaced squares, the present disclosure is not limited to this. The grid pattern for scanning may be set, for example, as a grid pattern with a finer number of squares. Furthermore, in relation to the chromatic aberration of magnification characteristics of the fθ lens, the grid spacing of the grid pattern may be narrowed in areas requiring particularly high accuracy. Furthermore, a radial grid pattern may be set. However, in this embodiment, since the correction angle is set on two axes, the x-axis and the y-axis, the orthogonal grid pattern shown in FIG. 4 is more preferable.

[0072] Therefore, when the processing light locus 28 and the measurement light locus 27 shown in FIG. 4 are compared, it is found that a deviation occurs at each corresponding lattice point of the lattice pattern.

[0073] In other words, in order to create the correction table data, it is necessary to determine the correction amount so that a processing light lattice point 30, which is a certain lattice point on the processing light trajectory 28, coincides with the corresponding measurement light lattice point 29 on the measurement light trajectory 27.

[0074] <Calculation method of correction angle> Next, a method for calculating a correction angle at a predetermined grid point position will be described with reference to FIG.

[0075] FIG. 5 is a flowchart showing a method for calculating the correction angle at a predetermined processing beam lattice point 30.

[0076] For ease of explanation, the following description will be given assuming that the x-axis of first mirror 13 coincides with the x-axis of second mirror 17, and that the y-axis of first mirror 13 coincides with the y-axis of second mirror 17. The description will also be given assuming that the scanning angle of first mirror 13 is (φx, φy) and the correction angle of second mirror 17 is (ψx, ψy).

[0077] As shown in FIG. 5, first, the control unit 6 of the laser processing device 1 sets a processing light lattice point 30 (an example of a target position) for which a correction angle is to be obtained (step S1).

[0078] Next, the control unit 6 selects the axis of the correction angle to be obtained (step S2).

[0079] Specifically, for example, the x-axis or y-axis is selected in the grid pattern shown in Fig. 4. The following description will be given taking as an example a case where the y-axis is selected as the axis of the correction angle to be obtained. Note that if the x-axis is selected, the x-axis and y-axis can be interchanged in the following description.

[0080] Next, the control unit 6 sets a processing section Wx passing through the processing light lattice point 30 in the direction of an axis perpendicular to the axis of the selected correction angle, for example, as shown in FIG. 6 (step S3).

[0081] 6 is a diagram schematically showing an example of a processing section Wx and a data acquisition section Mx (details will be described later) that are set when the y-axis is selected as the axis of the correction angle to be obtained. Specifically, for example, in step S3, as shown in FIG. 6, a processing section Wx that passes through the processing light lattice point 30 in the x-axis direction orthogonal to the selected y-axis is set. This determines the operation schedule of the first mirror 13 during processing.

[0082] Next, the control unit 6 sets a data acquisition section Mx (an example of a measurement section) centered on the processing light lattice point 30 within the set processing section Wx (step S4). Specifically, for example, in step S4, as shown in Fig. 6, a data acquisition section Mx centered on the processing light lattice point 30 is set within the set processing section Wx.

[0083] Next, the control unit 6 sets a plurality of data acquisition positions 38 in a direction perpendicular to the machining direction within the set data acquisition section Mx (step S4). Specifically, for example, in step S5, as shown in Fig. 6, data acquisition positions 38 (38a, 38b, 38c) in the y-axis direction orthogonal to the machining direction (direction of the machining section Wx, for example, the x-axis direction) are set within the set data acquisition section Mx.

[0084] At this time, scanning in a direction perpendicular to the processing direction of the data acquisition position 38 (for example, the y-axis direction) is performed by the operation of only the second mirror 17. Furthermore, the scanning range of the second mirror 17 is constant regardless of the data acquisition position 38. In other words, the position of the data acquisition position 38 in the processing direction is determined as the position of the first mirror 13 during processing. As a result, an operation schedule is determined such that the second mirror 17 operates only at the specified data acquisition position 38, for example, as shown in FIG. 7 below.

[0085] FIG. 7 is a diagram showing a schematic diagram of the relationship between the processing point 20 during processing and the data acquisition position 38.

[0086] 7, the data acquisition position 38 follows a locus on the keyhole 22 that is perpendicular to the processing direction (for example, the x-axis direction). The positional relationship between the processing point 20 and the data acquisition position 38 in the processing direction is the same except for the influence of the positional deviation between the processing laser beam 11 and the measurement beam 15 due to the chromatic aberration of magnification of the lens 14. Therefore, the data acquisition position 38a, the data acquisition position 38b, and the data acquisition position 38c shown in FIG. 6 are approximately the same position (including the same position) in the processing direction on the keyhole 22.

[0087] In addition, in Figure 6, an example is shown in which data acquisition positions 38 are set at three locations: data acquisition position 38a, data acquisition position 38b, and data acquisition position 38c. However, in practice, it is preferable to set data acquisition positions 38 at more than three locations.

[0088] Furthermore, it is preferable to set the scanning range of the data acquisition position 38 in the direction perpendicular to the processing direction as follows. Specifically, first, a correction angle at which the measurement beam 15 is positioned at the processing beam lattice point 30 is determined by optical simulation. Then, the scanning range of the data acquisition position 38 is set with the determined correction angle as the center. As a result, the difference between the position of the processing point 20 in the processing direction shown in FIG. 7 and the position of the data acquisition position 38 is the difference between the correction angle determined by optical simulation and the actual correction angle. As a result, it is possible to measure the position of the keyhole 22 at a position closer to the processing point 20.

[0089] The reason for setting the data acquisition position in the direction perpendicular to the processing direction will be explained below with reference to FIGS. 8 to 11. FIG.

[0090] Here, the position of the keyhole 22 coincides with the position of the processing point 20 of the processing laser beam 11. In other words, for example, by determining the center position of the shape of the keyhole 22 at the processing beam lattice point 30, the measuring beam 15 can be made to coincide with the processing beam lattice point 30.

[0091] 8 to 11 show examples of the measurement results of the shape of the keyhole 22. FIG.

[0092] Specifically, Fig. 8 is a graph showing an example of the results of measuring the shape of the keyhole 22 in the x direction by the laser processing apparatus 1 when the processing direction is the +x direction. Fig. 9 is a graph showing an example of the results of measuring the shape of the keyhole 22 in the x direction by the laser processing apparatus 1 when the processing direction is the -x direction. Fig. 10 is a graph showing an example of the results of measuring the shape of the keyhole 22 in the y direction by the laser processing apparatus 1 when the processing direction is the +x direction. Fig. 11 is a graph showing an example of the results of measuring the shape of the keyhole 22 in the y direction by the laser processing apparatus 1 when the processing direction is the -x direction.

[0093] The measurement results shown in Figures 8 to 11 each show the shape of the keyhole 22 at the processing origin 26. Note that the measurement results shown in Figures 8 to 11 are average output values ​​obtained by performing measurements multiple times using a method different from that of this embodiment.

[0094] Here, the vertical axis in the drawing indicates the depth z of the keyhole 22 measured by the optical interferometer 3. The horizontal axis in the drawing indicates the coordinates of the processed surface 19 (unit: μm).

[0095] First, to determine the center position of the keyhole 22, the center position of the shape crossing the threshold value Zth in the depth direction was determined. As a result, the center position x of the keyhole 22 in the processing direction was −15 μm when the processing direction was +x, as shown in FIG. 8. On the other hand, when the processing direction was −x, it was 5 μm, as shown in FIG. 9. In other words, it was confirmed that a difference of 20 μm occurs depending on the processing direction.

[0096] It is generally known that the shape of the keyhole 22 in the processing direction has a slight tail on the rear side of the processing direction due to the influence of the viscosity of the molten metal. Therefore, it is thought that the above difference is caused by the deviation of the center position of the keyhole 22 due to the difference in the processing direction.

[0097] Furthermore, the center position y of the keyhole 22 perpendicular to the processing direction is −20 μm when the processing direction is +x, as shown in Figure 10. On the other hand, when the processing direction is −x, it is −20 μm, as shown in Figure 11. That is, it was confirmed that the center position y of the keyhole 22 is reproducible (the same) regardless of the processing direction.

[0098] In other words, by measuring the shape of the keyhole 22 perpendicular to the processing direction, it is possible to more accurately determine the position of the keyhole 22. For this reason, in this embodiment, the data acquisition position 38 is set in the direction perpendicular to the processing direction.

[0099] Next, the control unit 6 performs processing on the processing surface 19 and acquires a plurality of measurement data (step S6). The plurality of measurement data is data indicating the measurement results at each of the plurality of data acquisition positions 38.

[0100] For example, if the y-axis is selected, in step S6, measurement data corresponding to each of the data acquisition positions 38a, 38b, and 38c is acquired during processing of the processing section Wx shown in Fig. 6. Then, when processing is completed, processing marks 39 (see Fig. 14) are formed in the x-axis direction in the processing section Wx. Note that if the x-axis is selected, processing marks 39 (see Fig. 14) are formed in the y-axis direction.

[0101] Next, the control unit 6 creates projection data by overlapping the acquired plurality of measurement data so as to project them in the processing direction (step S7).

[0102] A specific example of step S7 for creating projection data will be described below with reference to FIG.

[0103] FIG. 12 is a graph for explaining an example of overlapping a plurality of measurement data.

[0104] Note that positions a, b, and c shown in FIG. 12 correspond to data acquisition positions 38a, 38b, and 38c shown in FIG. 6, respectively.

[0105] The measurement data corresponding to the data acquisition positions 38a, 38b, and 38c are each represented by a vertical axis representing the depth z (vertical axis) measured by the optical interferometer 3 and a horizontal axis representing the correction angle ψy (horizontal axis) in the scanning direction of the data acquisition position 38.

[0106] The points in the graphs for positions a, b, and c are depth data measured by the optical interferometer 3 at the respective ψy coordinate positions. As shown in Fig. 7, the data acquisition position 38 is perpendicular to the processing direction on the keyhole 22. Therefore, the graphs for positions a, b, and c are equivalent to the results of measuring a cross section perpendicular to the processing direction of the keyhole 22.

[0107] In this case, to find the correction angle of the processing light lattice point 30, the center position of the keyhole 22 can be found from the graph of position b. However, there is little valid data representing the shape of the keyhole 22 in each point cloud data. Therefore, it is not possible to find the center position of the keyhole 22 with sufficient accuracy.

[0108] Furthermore, positions a, b, and c are data acquired at different scanning angles of the lens 14. Therefore, the ψy coordinate A, ψy coordinate B, and ψy coordinate C of the center position of the keyhole 22 at positions a, b, and c are shifted due to the influence of chromatic aberration of magnification of the lens 14.

[0109] Here, the chromatic aberration of magnification can be approximated linearly within a narrow range. Therefore, with coordinate B of position b of the processing light lattice point 30 as the center, the distance between coordinates A and B and the distance between coordinates B and C almost coincide (including coincidence).

[0110] Therefore, in this embodiment, point cloud data of the graphs of positions a, b, and c are created as data in which the data are superimposed at the same coordinates (see the graph shown at the bottom of FIG. 12).

[0111] That is, as shown in Fig. 6, data acquisition positions 38a, 38b, and 38c are perpendicular to the machining section Wx. Therefore, the overlapped graph shown in Fig. 12 is projection data obtained by projecting and overlapping the graphs of positions a, b, and c in the machining direction.

[0112] At this time, the projection data is a superposition of distributions of point cloud data at positions a and c, which are shifted equally to the left and right with the center at position b of the processing light lattice point 30. Therefore, the center position P of the projection data coincides with the coordinate B of the center position of position b of the processing light lattice point 30.

[0113] Therefore, if the center position P of the projection data is obtained, the correction angle of the processing light lattice point 30 can be obtained. By adopting the above method, it is possible to increase the amount of effective data for obtaining the correction angle of the processing light lattice point 30 without being affected by chromatic aberration of magnification. This makes it possible to improve the measurement accuracy of the depth of the keyhole 22.

[0114] Next, the control unit 6 determines the correction angle for the selected axis based on the above-mentioned projection data.

[0115] A specific example of step S8 will be described below with reference to Fig. 13. Fig. 13 is a graph for explaining an example of determining a correction angle from projection data.

[0116] Typically, the keyhole 22 is formed by the pressure of the vapor generated when the molten metal evaporates, and so its shape is constantly changing. Therefore, the point cloud data in the graph of FIG. 13 is distributed in the depth z direction. At this time, the bottom of the keyhole 22 is at the deepest position. Therefore, the area near the lowest point of the point cloud data is extracted. This allows for a shape distribution 40 of the data acquisition position 38 to be obtained.

[0117] Specifically, for example, a process is performed in the direction of the correction angle ψy axis to extract 5th percentile data with small z values ​​from point cloud data present within a certain section in the direction of the correction angle ψy axis. This allows a shape distribution 40 of the data acquisition positions 38 to be obtained. Then, a center position P of two points where the obtained shape distribution 40 of the data acquisition positions 38 crosses the threshold value Zth in the depth direction is determined. This allows the correction angle of the y axis of the processing light lattice point 30 to be determined.

[0118] Next, the control unit 6 determines whether or not the correction angles for the x-axis and y-axis at which the first mirror 13 and the second mirror 17 rotate have been obtained (step S9). If data for both the x-axis and the y-axis have been obtained (YES in step S9), the flow ends.

[0119] On the other hand, if data for both the x-axis and the y-axis have not been acquired (NO in step S9), the process returns to step S2. Specifically, for example, if the y-axis is selected in step S2 and the correction angle for the y-axis is calculated in step S8, the process returns to step S2, and the x-axis is selected in step S2. Then, the correction angle for the x-axis is calculated through steps S3 to S8.

[0120] According to the above-described flow, the correction angle (ψx, ψy) at the scanning angle (φx, φy) of a predetermined processing light lattice point 30 can be obtained.

[0121] After the above-described flow is completed, cross-shaped processing marks 39 that intersect at processing light lattice points 30 are formed on the processing surface 19 as shown in FIG.

[0122] That is, the above-described method can determine the correction angle of the processing beam lattice point 30 with an accuracy of 10 μm or less.

[0123] Therefore, the above-described method is suitable when a laser with excellent beam quality (for example, a single-mode fiber laser) is used in the processing head 2 of the present disclosure. That is, in the case of a single-mode fiber laser, the beam diameter of the processing laser beam 11 at the processing point 20 is 50 μm or less. Therefore, the above-described method, in which the accuracy of the correction angle at the processing light lattice point 30 is 10 μm or less, is more effective even when a single-mode fiber laser is used.

[0124] <How to create correction table data> Next, a method for creating the corrected number table data will be described with reference to Fig. 15. Fig. 15 is a flowchart showing the method for creating the corrected number table data.

[0125] 15, first, the control unit 6 of the laser processing device 1 sets a grid pattern (for example, the processing light locus 28 shown in FIG. 4) that is the range to be laser processed on the processing surface 19 of a temporary workpiece 18 (for example, a metal flat plate) (step S11). Then, one grid point is selected from a plurality of grid points included in the grid pattern.

[0126] Next, the control unit 6 uses the method shown in FIG. 5 to determine the correction angle based on the measurement data in the direction perpendicular to the processing direction (step S12).

[0127] Next, the control unit 6 stores the correction angle calculated in step S12 and the scan angle at that time in the memory 31 as correction number table data (step S13).

[0128] Next, the control unit 6 determines whether or not the correction number table data has been saved for all the grid points of the grid pattern set in step S11 (step S14). At this time, if the correction number table data has been saved for all the grid points (YES in step S14), the control unit 6 ends the flow.

[0129] On the other hand, if correction number table data has not been stored at all grid points (NO in step S14), the control unit 6 selects one new grid point (i.e., a grid point at which correction number table data has not been stored) (step S15). Thereafter, the control unit 6 returns the flow to step S12 and executes the subsequent steps.

[0130] The correction table data can be obtained by the method described above.

[0131] Furthermore, by carrying out the above-described method, as shown in FIG. 16, a plurality of cross-shaped processing marks 39 are formed on the processing surface 19 in correspondence with all of the processing light lattice points 30 (see FIG. 4).

[0132] If the grid pattern set in step S11 is the 4x4 grid pattern shown in Fig. 4, correction number table data can only be created for 16 grid points. Therefore, as described above, it is more preferable to set a grid pattern that includes 16 or more grid points. This allows more correction number table data to be created.

[0133] However, even if a large amount of correction table data is created, the scan angle of first mirror 13 can be set to any value within the mechanical operating range. Therefore, there may be cases where the scan angle of first mirror 13 does not match the created correction table data. In such cases, it is necessary to interpolate the correction table data to find the correction angle.

[0134] The method of finding the correction angle by interpolating the correction table data will be described later.

[0135] <Processing data> Next, the machining data used to machine the workpiece 18 will be described.

[0136] In conventional laser processing devices with an fθ lens and a galvanometer mirror, a control unit controls the laser oscillator and the galvanometer mirror using multiple processing data sets set in a time series. This allows processing to be performed in a time series at each processing point on the surface of the workpiece. Note that the processing data is, for example, a set of output command values ​​to the laser oscillator and data items for the scanning angle and processing speed for each processing point. Here, the output command value indicates the oscillation intensity of the processing laser light.

[0137] However, in the laser processing device 1 of this embodiment, a correction angle is added as data items of the processing data used by the laser processing device 1 in addition to the output instruction value to the laser oscillator 5 (laser output data), the position of the processing point 20 (processing point position), and the scan angle. In the following explanation, the processing data to which the correction angle is added as a data item will be referred to as "corrected processing data."

[0138] An example of the corrected processed data will be described below with reference to Fig. 17. Fig. 17 is a diagram showing an example of the configuration of the corrected processed data.

[0139] As shown in FIG. 17, the corrected processing data is a set of data items, including data number k, laser output data L k , machining point position x k , machining point position y k , scanning angle φx k , scanning angle φy k , correction angle ψx k , correction angle ψy k Includes:

[0140] The data number k indicates the order of the processing data. Laser output data L k indicates the output instruction value to the laser oscillator 5. Processing point position x k indicates the position of the machining point 20 in the x direction. Machining point position y k indicates the position of the processing point 20 in the y direction. k indicates the scanning angle of the first mirror 13 that is responsible for scanning in the x direction. kindicates the scanning angle of the first mirror 13 that is responsible for scanning in the y direction. k indicates the correction angle of the second mirror 17 that corrects the position of the measuring beam 15 in the x direction. k indicates the correction angle of the second mirror 17 that corrects the position of the measuring beam 15 in the y direction.

[0141] 17, the subscript k added to each data item other than the data number k indicates that the data item corresponds to the data number k. The scanning angle in the corrected processed data is an example of a first instruction value. The correction angle in the corrected processed data is an example of a second instruction value.

[0142] As described above, the corrected processed data is configured.

[0143] A method for creating processed data (corrected processed data) will be described below with reference to Fig. 18. Fig. 18 is a flowchart showing the method for creating processed data.

[0144] 18, the control unit 6 of the laser processing device 1 first sets the data number k to be referenced to zero (0) (step S21). The data number k is assigned to an area in the memory 31 where the processing data is stored.

[0145] Next, the control unit 6 writes the laser output data L k , machining point position x k , y k These values ​​are set (saved) by the user of the laser processing device 1 using an operation unit (e.g., a keyboard, a mouse, a touch panel, etc.) not shown in the figure in order to achieve the desired laser processing.

[0146] Next, the control unit 6 determines the machining point position x set in step S22. k , y k Based on this, the scanning angle φx of the first mirror 13 k ,φy kCalculate the scan angle φx k ,φy k is stored in the area of ​​data number k in the memory 31 (step S23). At this time, if the focal length of the lens 14 is f, there is a relationship between the processing point position and the scanning angle, (x k ,y k )=(2f·φx k ,2f·φy k ) relationship exists. Therefore, the scanning angle is automatically determined from the machining point position.

[0147] The relational expression between the processing point position and the scanning angle, the correspondence number table, etc. may be set in advance by the user. In this case, the scanning angle φx of the first mirror 13 is further calculated using the relational expression between the processing point position and the scanning angle, the correspondence number table, etc. k ,φy k may be determined.

[0148] Next, the control unit 6 determines whether or not the setting of the processing data has been completed for all data numbers k (step S24). At this time, if the setting of the processing data has been completed for all data numbers k (YES in step S24), the control unit 6 ends the flow.

[0149] On the other hand, if the setting of processing data has not been completed for all data numbers k (NO in step S24), the control unit 6 increments the referenced data number k by 1 (step S25). After that, the control unit 6 returns the flow to step S22 and executes the subsequent steps.

[0150] In this way, processed data (corrected processed data) is set for all data numbers k.

[0151] <How to set the correction angle> Next, a method for setting a correction angle (second instruction value) for each machining point position for each machining data set by the flow of FIG. 18 will be described with reference to FIGS. 19 and 20. FIG.

[0152] First, the configuration of the correction number table data for the machining position will be described with reference to Fig. 19. Fig. 19 is a diagram showing a correction number table 34 for the machining position that schematically shows the configuration of the correction number table data for the machining position.

[0153] 19 schematically shows the corrected machining data set for each grid point on the machining surface 19 as data points 32. As described above, each data point 32, which is the corrected machining data, includes a position on the machining surface 19 (i.e., machining point position), a scanning angle, and a correction angle. Note that the corrected data point 33 shown in FIG. 19 is a point corresponding to the machining origin 26 on the machining surface 19.

[0154] In the following description, the position of each data point 32 in the processing position correction number table 34 will be represented by a scanning angle (φx, φy) for convenience. The data number in the direction corresponding to the scanning angle φx will be represented as i, and the data number in the direction corresponding to the scanning angle φy will be represented as j.

[0155] At this time, each data point 32 is a scan angle (Φx i ,Φy j ) and the correction angle for the correction table (Ψx ij ,Ψy ij ) and (Φx i ,Φy j ,Ψx ij ,Ψy ij ) is stored. In other words, the scanning angle for the correction table (Φx i ,Φy j ) has elements of scan angles (φx, φy).

[0156] Next, a method for setting the correction angle (second command value) will be described with reference to Fig. 20. Fig. 20 is a flowchart showing the method for setting the correction angle.

[0157] In step S31, the control unit 6 of the laser processing device 1 sets the data number k to be referenced to zero (0).

[0158] As shown in FIG. 20, the control unit 6 first sets the data number k to be referenced to zero (0) (step S31).

[0159] Next, the control unit 6 reads the scan angle (φx k ,φy k ) and the scanning angle (Φx i ,Φy j ) and the control unit 6 compares φx k =Φx i and φy k =Φy j (Step S32) Specifically, in step S32, the control unit 6 determines whether or not a data item including the exact same scan angle as the scan angle set by the user exists in the processing position correction number table 34.

[0160] At this time, φx k =Φx i and φy k =Φy j If there are data numbers i and j such that φx k =Φx i and φy k =Φy j If there is no data number i, j that satisfies the above condition (NO in step S32), the control unit 6 advances the flow to step S34.

[0161] Then, in step S33, the control unit 6 calculates φx k =Φx i and φy k =Φy j Using the data numbers i and j, the correction angle is (ψx k ,ψy k )=(Ψx ij ,Ψy ij ) In other words, in this step S33, since there is a data item including the exact same scanning angle as the scanning angle set by the user, the control unit 6 sets the corresponding correction angle for the correction number table as the correction angle as is.

[0162] In step S34, the control unit 6 calculates the scanning angle (φx k ,φy k ) is interpolated using the data of the four closest points surrounding the k ,ψy k ) is set. Details of step S34 will be described later.

[0163] Next, the control unit 6 calculates the correction angle (ψx k ,ψy k ) is set (saved) in the area of ​​data number k of the processing data in the memory 31 (step S35).

[0164] Next, the control unit 6 determines whether or not the setting of the correction angle has been completed for all of the processing data stored in the memory 31 (step S36). At this time, if the setting of the correction angle has been completed for all of the processing data (YES in step S36), the control unit 6 ends the flow.

[0165] On the other hand, if the setting of the correction angles has not been completed for all of the processing data (NO in step S36), the control unit 6 increments the reference data number k by 1 (step S37). Thereafter, the control unit 6 returns the flow to step S32 and executes the subsequent steps.

[0166] As described above, correction angles are set for all data numbers k in the processing data set by the flow shown in Fig. 18. In other words, corrected processing data is generated.

[0167] <Interpolation process details> Next, the interpolation process in step S34 shown in FIG. 20 will be described in detail with reference to FIG.

[0168] The interpolation process in step S34 is performed based on the scan angle (φx k ,φy k ) is the scan angle (Φx i,Φy j ) is not matched.

[0169] Figure 21 shows the scanning angle X (φx k ,φy k ) is the scanning angle (Φx i ,Φy j ) does not match the scan angle X (φx k ,φy k ) and its surrounding correction data points.

[0170] As shown in Figure 21, the scan angle X (φx k ,φy k ,ψx k ,ψy k ) corresponds to the correction data point A(Φx i ,Φy j ,Ψx ij ,Ψy ij ), correction data point B(Φx i+1 ,Φy j ,Ψx i+1j ,Ψy i+1j ), correction data point C(Φx i ,Φy j+1 ,Ψx ij+1 ,Ψy ij+1 ), correction data point D(Φx i+1 ,Φy j+1 ,Ψx i+1j+1 ,Ψy i+1j+1 ) is located in the lattice made by the four points. i ≦φx k ≦Φx i+1 (The equality does not hold simultaneously), Φy j ≦φy k ≦Φy j+1 The relationship (the equality sign cannot be true at the same time) holds true.

[0171] And the correction angle (ψx k ,ψy k ) is the scan angle X(φx k ,φy k) and the values ​​of the correction data points A, B, C, and D, it can be calculated by the following equations (1) and (2). ψx k =(EΨx ij +FΨx i+1j +GΨx ij+1 +HΨx i+1j+1 ) / J···(1) ψy k =(EΨy ij +FΨy i+1j +GΨy ij+1 +HΨy i+1j+1 ) / J···(2)

[0172] Note that E, F, G, H, and J in formulas (1) and (2) can be calculated from formulas (3) to (7) shown below. E=(φx k -Φx i )(φy k -Φy j )·····(3) F=(Φx i+1 -φx k )(φy k -Φy j )····(4) G=(φx k -Φx i )(Φy j+1 -φy k )····(5) H=(Φx i+1 -φx k )(Φy j+1 -φy k )···(6) J=(Φx i+1 -Φx i )(Φy j+1 -Φy j )···(7)

[0173] By the above-described interpolation process, the correction angle can be calculated based on the scanning angle set by the user.

[0174] In the above-mentioned interpolation process, an example using linear interpolation has been described, but the present invention is not limited to this. For example, a known two-dimensional interpolation method (spline interpolation, quadric surface approximation, etc.) may be used as the interpolation process. In addition, as the interpolation process, the correction angle (Ψx ij ,Ψy ij ), a high-order approximate continuous curved surface of the correction angle for the scan angle may be calculated, and the correction angle corresponding to the scan angle may be calculated.

[0175] <Laser processing method> Next, a laser processing method using the laser processing device 1 will be described with reference to FIG.

[0176] FIG. 22 is a flowchart showing the laser processing method.

[0177] As shown in FIG. 22, first, the control unit 6 of the laser processing device 1 sets the data number k to be referenced to zero (0) (step S41).

[0178] Next, the control unit 6 calculates the corrected processing data (laser output data L k , scanning angle (φx k ,φy k ), correction angle (ψx k ,ψy k )) is read from the memory 31 (step S42).

[0179] Next, the control unit 6 reads out the scan angle (φx k ,φy k ), the first mirror 13 is operated based on the correction angle (ψx k ,ψy k ) and then operates the second mirror 17 (step S43).

[0180] Specifically, the control unit 6 controls the first driver 7 to set the scanning angle (φx k ,φy k ) to the first driver 7. As a result, the first driver 7 notifies the scan angle (φx k ,φy k), the control unit 6 controls the second driver 8 to operate the first mirror 13 based on the correction angle (ψx k ,ψy k ) is notified. As a result, the second driver 8 notifies the correction angle (ψx k ,ψy k ) the second mirror 17 is operated.

[0181] Next, the control unit 6 reads out the laser output data L k Based on this, the laser oscillator 5 oscillates the processing laser light 11.

[0182] Specifically, the control unit 6 receives laser output data L k to the laser oscillator 5. As a result, the laser oscillator 5 receives the laser output data L k Based on this, the processing laser light 11 is oscillated.

[0183] Next, the control unit 6 determines whether or not laser processing corresponding to all data numbers k stored in the memory 31 has been completed (step S44). At this time, if laser processing corresponding to all data numbers k has been completed (YES in step S45), the control unit 6 ends the flow.

[0184] On the other hand, if the laser processing corresponding to all data numbers k has not been completed (NO in step S45), the control unit 6 increments the data number k to be referenced by one (step S46).

[0185] Then, the control unit 6 returns the flow to step S42 and executes the subsequent steps.

[0186] Through the above flow, laser processing is performed for all data numbers k.

[0187] <Keyhole depth measurement method> Next, a method for measuring the depth of the keyhole 22 (see, for example, FIG. 1) when performing the above-described laser processing method will be described with reference to FIG.

[0188] FIG. 23 is a flowchart showing a method for measuring the depth of the keyhole 22.

[0189] First, the control unit 6 of the laser processing device 1 acquires position data of the processing surface 19 of the unprocessed workpiece 18 before starting the laser processing method shown in Fig. 22. The position data is data indicating the height of the processing surface 19 in the unprocessed state (in other words, the position of the processing surface 19 in the Z-axis direction shown in Fig. 1, etc.).

[0190] Next, as shown in FIG. 23, the control unit 6 issues a command to the measurement processing unit 4 to start measuring the depth of the keyhole 22 (step S51).

[0191] 22 is started, the measurement processing unit 4 causes the optical interferometer 3 to emit the measurement light 15. Then, the measurement processing unit 4 generates an optical interference signal according to the optical path difference between the measurement light 15 reflected and returned from the keyhole 22 and the reference light (step S52).

[0192] Next, the measurement processing unit 4 uses the position data and the generated optical interference signal to calculate the depth (i.e., penetration depth) of the keyhole 22. Then, the control unit 6 stores data indicating the calculated depth of the keyhole 22 (hereinafter referred to as "keyhole depth data") in the memory 31 (step S53).

[0193] Next, the control unit 6 determines whether or not to end the measurement of the depth of the keyhole 22 (step S54). At this time, if the measurement is not to be ended (NO in step S54), the control unit 6 returns the flow to step S52 and executes the subsequent steps.

[0194] On the other hand, if the measurement is to be ended (YES in step S54), the control unit 6 issues a command to the measurement processing unit 4 to end measurement of the depth of the keyhole 22 after the laser processing method shown in FIG. 22 is completed (step S55).

[0195] The command to start measuring the depth of the keyhole 22 in step S51 and the command to end measuring the depth of the keyhole 22 in step S55 do not need to be executed by the control unit 6. For example, the user may execute the above commands using an operation unit (not shown). This allows, for example, the function of controlling the keyhole depth measurement to be separated from the function of controlling laser processing. This improves the degree of freedom in designing the laser processing apparatus 1.

[0196] <Effects> As described above, according to this embodiment, the laser processing apparatus 1 sets a processing section Wx that passes through processing light lattice point 30 on the processing surface 19, sets a data acquisition section Mx centered on processing light lattice point 30 within the processing section Wx, and sets a plurality of data acquisition positions 38 that are trajectories perpendicular to the processing direction within the data acquisition section Mx. Furthermore, during processing of the processing section Wx, the laser processing apparatus 1 acquires measurement data that indicates the shape of the keyhole 22 at each of the data acquisition positions 38, projects the measurement data in the processing direction to create superimposed projection data, and determines a second indication value (the correction angle of the second mirror 17) in the direction perpendicular to the processing direction at processing light lattice point 30 based on the projection data.

[0197] According to this configuration, it is possible to correct the deviation between the position where the processing laser beam 11 and the measurement beam 15 reach on the processing surface 19 after passing through the lens 14, which is caused by the chromatic aberration of magnification of the lens 14. This allows the optical interferometer 3 to appropriately measure the depth of the keyhole 22. As a result, it is possible to measure the depth of the keyhole more accurately.

[0198] Hereinafter, the result of correction of the chromatic aberration of magnification of the lens 14 in the laser processing apparatus 1 having the above configuration will be described with reference to FIG.

[0199] FIG. 24 is a diagram showing an example of the trajectories of the processing laser beam 11 and the measuring beam 15 on the processing surface 19 in a state in which the influence of chromatic aberration of magnification has been corrected by the operation of the second mirror 17. In FIG.

[0200] As shown in Figure 24, due to the above correction, the processing light trajectory 28, which is the trajectory of the processing laser light 11, the measurement light trajectory 27, which is the trajectory of the measurement light 15, and each lattice point are all consistent with each other, unlike in Figure 4.

[0201] The present disclosure is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present disclosure. Modifications will be specifically described below.

[0202] [Variation 1] In the above embodiment, the case where the second mirror 17, which is a galvanometer mirror, is used to change the optical axis direction of the measuring light 15 has been described as an example, but the present invention is not limited to this.

[0203] The second mirror used in the laser processing apparatus 1 is, for example, installed between the measurement light inlet 9 and the dichroic mirror 12, and can change the optical axis direction of the measurement light 15 based on the control of the control unit 6. For example, the second mirror 35 shown in FIG. 25 may be configured as such.

[0204] FIG. 25 is a diagram schematically showing the laser processing device 1 using the second mirror 35. As shown in FIG.

[0205] The laser processing apparatus 1 shown in Fig. 25 has a second mirror 35 instead of the second mirror 17 shown in Fig. 1 etc., and further has a moving stage 36 and a stage driver 37. It should be noted that the laser processing apparatus 1 shown in Fig. 25 does not have the collimating lens 16 shown in Fig. 1 etc.

[0206] The second mirror 35 is a parabolic mirror fixed between the measurement light introduction port 9 and the dichroic mirror 12. The second mirror 35 may be configured as a MEMS (Micro Electro Mechanical Systems) mirror or the like.

[0207] The moving stage 36 is provided at the measurement light inlet 9 .

[0208] The stage driver 37 is electrically connected to the control unit 6 and operates the moving stage 36 based on instructions from the control unit 6. This causes the moving stage 36 to move in the yz directions in FIG. 25 (see the up and down double-headed arrows in the figure). That is, the moving direction of the moving stage 36 is along two axes perpendicular to the measurement optical axis 23.

[0209] Furthermore, the exit end of the measurement light inlet 9 for the measurement light 15 is arranged to coincide with the focal point of the second mirror 35. As a result, the measurement light 15 is reflected by the second mirror 35, becomes parallel light, and travels toward the dichroic mirror 12.

[0210] At this time, the angle of the measurement optical axis 23 directed from the second mirror 35 to the dichroic mirror 12 changes due to the movement of the moving stage 36. This provides the same effect as when the second mirror 17, which is a galvanometer mirror, is used. [Industrial Applicability]

[0211] The laser processing apparatus and laser processing method of the present disclosure are useful, for example, in laser processing of automobiles, electronic components, and the like. [Explanation of symbols]

[0212] 1. Laser processing equipment 2 Processing heads 3 Optical interferometer 4 Measurement processing section 5 Laser oscillator 6 Control Unit 7 First Driver 8 Second Driver 9 Measurement light inlet 10 Processing light inlet 11,107 Laser beam for processing 12,110 Dichroic mirror 13 1st mirror 14 Lenses 15,105 measurement light 16 Collimating Lens 17,35 2nd mirror 18 Workpiece 19 Machining surface 20 processing points 21 Molten pool 22 Keyhole 23,23a,23b Measurement optical axis 24,24a Processing optical axis 25 Lens optical axis 26 Processing origin 27 Measurement light trajectory 28 Processing light trajectory 29 Measurement light grid point 30 processing optical lattice points 31 memory 32 data points 33,A,B,C,D correction data points 34 Correction Table 36 Moving Stage 37 Stage Driver 38, 38a, 38b, 38c Data acquisition location 39 Machining marks 40 Shape distribution 100 analytical units 101,104 Optical fiber 102 reference arm 103 Beam Splitter 106 Collimator Module 108 Welding Head 109 Measuring Arm 111 Condenser Lens 112 Workpiece 113 Processing Department A,B,C coordinates

Claims

1. a laser oscillator that irradiates a workpiece with processing light; an optical interferometer that irradiates the workpiece with measurement light and acquires an optical interference signal based on the measurement light and reference light reflected from the workpiece; a first mirror that changes the traveling direction of the processing light and the measuring light; a second mirror that changes the angle of incidence of the measurement light on the first mirror; a lens that focuses the processing light and the measurement light on a processing point; a measurement processing unit that measures the depth of a keyhole generated at the processing point based on the optical interference signal; A control unit; and In a laser processing apparatus, the first mirror and the second mirror are movable, A correction method for generating correction data related to a deviation in the arrival position of the measurement light on the workpiece caused by chromatic aberration of the lens, the method comprising: irradiating the workpiece with the processing light to form a three-dimensional shape; acquiring the correction data based on the three-dimensional shape; Correction method.

2. The three-dimensional shape is a processing mark extending along a first direction and a second direction intersecting the first direction. The correction method according to claim 1 .

3. the correction data includes a correction angle of the second mirror for eliminating a deviation of the arrival position of the measurement light. The correction method according to claim 1 or 2.

4. the control unit sets a plurality of processing light lattice points for determining the correction angle, and determines the correction angle of the second mirror in a direction perpendicular to the laser processing direction at one of the plurality of processing light lattice points; The correction method according to claim 3 .

5. The control unit determining a correction angle at a target position for each of the x-axis and y-axis along which the second mirror rotates; The correction method according to claim 4 .

6. a laser oscillator that irradiates a workpiece with processing light; an optical interferometer that irradiates the workpiece with measurement light and acquires an optical interference signal based on the measurement light and reference light reflected from the workpiece; a first mirror that changes the traveling direction of the processing light and the measuring light; a second mirror that changes the angle of incidence of the measurement light on the first mirror; a lens that focuses the processing light and the measurement light on a processing point; a measurement processing unit that measures the depth of a keyhole generated at the processing point based on the optical interference signal; a control unit, the first mirror and the second mirror are movable; irradiating the workpiece with the processing light to form a three-dimensional shape; acquiring correction data relating to a deviation of the arrival position of the measurement light on the workpiece caused by chromatic aberration of the lens based on the three-dimensional shape; Laser processing equipment.

7. The three-dimensional shape is a processing mark extending along a first direction and a second direction intersecting the first direction. The laser processing device according to claim 6.

8. the second mirror is a galvanometer mirror, the control unit determines a correction angle at a target position for each of the x-axis and the y-axis along which the second mirror rotates; 8. The laser processing device according to claim 6 or 7.

9. The lens is an fθ lens.

8. The laser processing device according to claim 6 or 7.

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