Laser processing apparatus and laser processing method

Abstract

To provide a laser processing device that can suppress damage to mirrors. [Solution] Laser beams are emitted from multiple output points. Each of the multiple laser beams emitted from the multiple output points is focused by a lens to form multiple focused laser beams. Each of the multiple focused laser beams is reflected by a mirror. The output points, lenses, and mirrors are configured to focus the multiple focused laser beams to a common point.

Description

Technical Field

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

Background Art

[0002] Laser processing apparatuses that use a laser for processing such as drilling and welding are known. In laser processing, for example, laser processing is performed by converging a collimated laser beam on a processing point to increase the fluence. When processing the side surface of a narrow groove, it is necessary to reflect the laser beam incident from the opening of the groove with a mirror disposed in the groove and make the laser beam incident on the side surface of the groove. A laser processing apparatus that outputs a plurality of imaging lenses so that an incident laser beam forms an image with a polygon mirror, and condenses the laser beams output from the plurality of imaging lenses and outputs them to a processing object is disclosed in Patent Document 1 below.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When processing the side surface of a recess such as a groove, depending on the dimensions of the recess, the distance from the mirror to the convergence point of the laser beam becomes short. When the distance from the mirror to the convergence point becomes short, the beam cross-section of the laser beam on the reflecting surface of the mirror becomes small, and as a result, the fluence becomes large. When the fluence of the laser beam becomes large, the mirror is likely to be damaged.

[0005] An object of the present invention is to provide a laser processing apparatus and a laser processing method capable of suppressing damage to a mirror.

Means for Solving the Problems

[0006] According to one aspect of the present invention, Multiple output points from which the laser beam is emitted, A lens that focuses each of the multiple laser beams output from the multiple output locations into multiple focused laser beams, A mirror that reflects each of the aforementioned multiple converged laser beams Equipped with, A laser processing apparatus is provided in which the output location, the lens, and the mirror are configured to focus the plurality of converged laser beams to a common point.

[0007] According to another aspect of the present invention, A beam scanner that scans the incoming laser beam, A lens that focuses the laser beam scanned by the beam scanner into a focused laser beam, A mirror is positioned at the location where the converged laser beam is incident and reflects the scanned converged laser beam. Equipped with, A laser processing apparatus is provided, in which the beam scanner, the lens, and the mirror are configured to focus the scanned converged laser beam to a single point.

[0008] According to yet another aspect of the present invention, Multiple mirrors are placed inside the recess of the workpiece, The laser beams emitted from multiple output points are focused into multiple focused laser beams. A laser processing method is provided in which each of the multiple focused laser beams is reflected by the multiple mirrors and focused to a common point on the side surface of the recess for processing. [Effects of the Invention]

[0009] By focusing multiple focused laser beams to a common point, the power of each focused laser beam can be reduced. This reduces the fluence of the focused laser beam at the mirror's reflective surface. Furthermore, when a laser beam is scanned with a beam scanner to form a focused laser beam, the position at which it enters the mirror's reflective surface changes over time. Therefore, the power entering the same point on the mirror's reflective surface per unit time decreases.

[0010] Damage to the mirror is suppressed by reducing the fluence or power per unit time at the reflective surface of the mirror. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic perspective view of a laser processing apparatus according to the first embodiment. [Figure 2] Figure 2 is a schematic perspective view of the vicinity of the laser barrel 10 of the laser processing apparatus according to the first embodiment. [Figure 3] Figure 3 is a schematic cross-sectional view of the lens barrel 10, the mirror box 20, and the workpiece 50. [Figure 4] Figure 4 is a schematic cross-sectional view of the lens barrel 10, mirror box 20, and workpiece 50 when welding is performed. [Figure 5] Figure 5 is a flowchart showing the processing procedure of the laser processing method according to the first embodiment. [Figure 6] Figure 6 is a schematic cross-sectional view of the laser barrel 10, mirror box 20, and workpiece 50 of the laser processing apparatus according to the second embodiment. [Figure 7] Figure 7 is a schematic perspective view of a laser processing apparatus according to the third embodiment. [Figure 8] Figure 8 is a schematic perspective view of a laser processing apparatus according to the fourth embodiment. [Figure 9] Figure 9 is a schematic perspective view of a laser processing apparatus according to a modified example of the fourth embodiment. [Modes for carrying out the invention]

[0012] Referring to FIGS. 1 to 5, a laser processing apparatus and a laser processing method according to the first embodiment will be described.

[0013] FIG. 1 is a schematic perspective view of a laser processing apparatus according to the first embodiment. The laser processing apparatus according to the first embodiment, as an example, performs laser processing by causing a laser beam to enter the side surface of a groove 51 formed in a workpiece 50.

[0014] Three laser beams output from a plurality of, for example, three laser light sources 40 are respectively guided to a lens barrel 10 via a laser light guiding optical system 41. As the laser light source 40, for example, a fiber laser oscillator that outputs a pulsed laser beam in the near-infrared region can be used. As the laser light guiding optical system 41, for example, a laser transmission fiber is used.

[0015] Each of the plurality of lens barrels 10 includes a lens inside, and the converged laser beam converged by the lens enters a mirror box 20. The tip of the mirror box 20 is disposed in the groove 51 of the workpiece 50. The plurality of converged laser beams output from the plurality of lens barrels 10 and incident in the mirror box 20 are reflected by a mirror in the mirror box 20 and condensed on the processed portion on the side surface of the groove 51.

[0016] The plurality of lens barrels 10 and the mirror box 20 are held by a robot arm 62. A system control unit 60 controls the laser light source 40 and a robot control unit 61, and the robot control unit 61 controls the robot arm 62. By operating the robot arm 62 by the system control unit 60 and the robot control unit 61, the tip of the mirror box 20 can be positioned in the groove 51 of the workpiece �0.

[0017] Figure 2 is a schematic perspective view of the laser barrel 10 and its vicinity in a laser processing apparatus according to the first embodiment. Multiple laser barrels 10 each emit a focused laser beam 15. The multiple focused laser beams 15 are incident on a mirror 21 housed in a mirror box 20 (Figure 1). The mirror box 20 is not shown in Figure 2.

[0018] A mirror 21 is positioned for each focused laser beam 15, and multiple mirrors 21 reflect each of the incident focused laser beams 15. The reflective surface of each of the multiple mirrors 21 is, for example, a plane. The multiple mirrors 21 are arranged within the groove 51, along the longitudinal direction of the groove 51. For example, the multiple mirrors 21 are arranged along a single straight line. The focused laser beams 15 reflected by the multiple mirrors 21 are focused to a common point (workpiece point P) on the side surface of the groove 51. For example, each of the focused laser beams 15 changes its direction of travel by 90° due to reflection by the mirror 21. After being reflected by the mirrors 21, the multiple focused laser beams 15 propagate along a common, imaginary plane.

[0019] Figure 3 is a schematic cross-sectional view of the lens barrel 10, mirror box 20, and workpiece 50. Since the structure of multiple lens barrels 10 (Figure 2) is identical, only one lens barrel 10 is shown in Figure 3. The output terminal of the laser light guide optical system 41 is fixed to the lens barrel 10. A divergent laser beam is output from the output terminal of the laser light guide optical system 41. The location where the divergent laser beam is output is referred to as the laser beam output location 11.

[0020] A collimating lens 12 and a focusing lens 13 are housed within the lens barrel 10. The diverging laser beam emitted from the output point 11 is collimated by the collimating lens 12 and then focused by the focusing lens 13. The combination of the collimating lens 12 and the focusing lens 13 forms a focused laser beam 15.

[0021] The focused laser beam 15 is reflected by a mirror 21 housed in a mirror box 20 and focused to a workpiece point P on the side surface of the groove 51 of the workpiece 50. As shown in Figure 2, multiple focused laser beams 15 are focused to a single common workpiece point P (the rear focal point of the focus lens 13). For example, the focused laser beam 15 output from the lens barrel 10 propagates in the depth direction of the groove 51, is reflected by the mirror 21, and then incident on the side surface of the groove 51. The incident of the focused laser beam 15 on the side surface of the groove 51 forms a recess 52. By moving the lens barrel 10 and mirror box 20 relative to the workpiece 50, a groove consisting of a series of recesses 52 can be formed on the side surface of the groove 51.

[0022] Multiple focusing lenses 13 (Figure 3) are used, each having the same focal length. Therefore, the optical path length from the focusing lens 13 to the workpiece point P is the same among the multiple focused laser beams 15. As shown in Figure 2, the distance from each of the reflection points of the multiple mirrors 21 to the workpiece point P is different among the focused laser beams 15. In order to make the optical path length from the focusing lens 13 to the workpiece point P the same, the distance from the focusing lens 13 to the mirror 21 is also set to be different among the focused laser beams 15.

[0023] Figure 4 is a schematic cross-sectional view of the lens barrel 10, mirror box 20, and workpiece 50 when welding is performed. The workpiece 53 is temporarily fixed to the side surface of the groove 51, and welding can be performed by irradiating the workpiece point P that overlaps with the edge of the workpiece 53 with a focused laser beam 15.

[0024] Next, with reference to Figure 5, the processing procedure of the laser processing method according to the first embodiment will be described. Figure 5 is a flowchart showing the processing procedure of the laser processing method according to the first embodiment.

[0025] First, the system control unit 60 (Figure 1) drives the robot arm 62 (Figure 1) via the robot control unit 61 (Figure 1) to position the mirror 21 (Figure 2) in the groove 51 of the workpiece 50 (Step S1). Furthermore, the robot arm 62 is driven to align the workpiece point P.

[0026] Subsequently, laser beams are emitted from each of the multiple laser light sources 40 (Figure 1). As a result, the divergent laser beams emitted from the multiple output points 11 (Figure 3) are focused to form multiple focused laser beams 15 (Step S2). Each of the multiple focused laser beams 15 is reflected by the mirror 21 and focused onto a common workpiece point P (Figure 2) on the side surface of the groove 51, thereby performing the processing (Step S3).

[0027] Next, we will describe the excellent effects of the first embodiment. In the first embodiment, the focused laser beam 15 is reflected by a plurality of mirrors 21 (Figure 2) placed within the groove 51, and then incident on the side surface of the groove 51. Therefore, compared to a configuration in which the focused laser beam 15 is directly incident on the workpiece point P without placing mirrors 21, it becomes possible to bring the incident angle of the focused laser beam 15 on the side surface of the groove 51 closer to 90°. This makes it possible to improve the processing quality.

[0028] The distance between the mirror 21 and the workpiece point P is constrained by the dimensions of the groove 51. For example, if the width of the groove 51 is about 20 mm, the distance from the reflective surface of the mirror 21 to the workpiece point P will be about 10 mm. Since the distance from the workpiece point P to the mirror 21 cannot be unconditionally increased, the beam cross-section of the focused laser beam 15 becomes smaller at the position of the mirror 21. As a result, the fluence of the focused laser beam 15 becomes high at the reflective surface of the mirror 21.

[0029] If the fluence of the focused laser beam 15 on the reflective surface becomes excessively high, the mirror 21 will be damaged. In the first embodiment, since the focused laser beam 15 incident on the workpiece point P is divided into multiple beams, the power of each of the multiple focused laser beams 15 becomes smaller, and the fluence on the reflective surface of the mirror 21 also becomes smaller. Therefore, damage to the mirror 21 can be suppressed.

[0030] Next, a modified example of the first embodiment will be described. In the first embodiment, multiple converged laser beams 15 are focused to a common workpiece point P, but it is not necessarily required that they be precisely focused to a single point geometrically. "Multiple converged laser beams 15 are focused to a common workpiece point P" can be interpreted as meaning that the beam cross-sections at the beam waists of the multiple converged laser beams 15 are focused in such a way that they overlap with each other. In other words, the beam cross-sections of all the converged laser beams 15 may overlap in at least a portion of the beam cross-sections at the beam waists of the multiple converged laser beams 15. Here, the beam cross-section at the beam waist refers to any beam cross-section within the depth of focus.

[0031] In the first embodiment (Figure 1), a robot arm 62 is used to move the lens barrel 10 and the mirror box 20, but other moving mechanisms may be used. For example, the lens barrel 10 and the mirror box 20 may be moved by combining multiple linear motion mechanisms. Alternatively, the lens barrel 10 and the mirror box 20 may be kept stationary, and the workpiece 50 may be moved.

[0032] In Figure 2, the number of lens barrels 10 and mirrors 21 is shown as three, but the number of lens barrels 10 and mirrors 21 is not limited to three. The number of lens barrels 10 and mirrors 21 may be two, or four or more. These numbers should be determined according to the fluence required for processing and the yield strength of the mirrors 21 against that fluence.

[0033] In the first embodiment, the case of machining the side surface of the groove 51 was described, but the shape of the area to be machined is not limited to a groove. For example, more generally, it is also possible to machine the side surface of a "recess".

[0034] Next, a laser processing apparatus according to the second embodiment will be described with reference to Figure 6. The configurations shared with the laser processing apparatus according to the first embodiment, as described with reference to Figures 1 to 5, will be omitted from this description.

[0035] Figure 6 is a schematic cross-sectional view of the laser barrel 10, mirror box 20, and workpiece 50 of the laser processing apparatus according to the second embodiment. In the first embodiment (Figure 3), the direction of travel of the multiple converged laser beams 15 is changed by 90° by the mirror 21. In the modified example shown in Figure 6, the angle of change in the direction of travel of the converged laser beams 15 is other than 90°. For example, as shown in Figure 6, the angle between the direction of travel of the converged laser beams 15 before incidence on the mirror 21 and the direction of travel of the converged laser beams 15 after reflection is less than 90°. For example, the workpiece point P where the multiple converged laser beams 15 are focused is located near the lower end of the side surface of the groove 51.

[0036] Next, the superior effects of the second embodiment will be described. By not limiting the angle of change in the direction of travel of the focused laser beam 15 to 90°, the degree of freedom in the relative positional relationship between the workpiece point P and the mirror 21 is increased. The angle of change in the direction of travel of the focused laser beam 15 should be determined in a way that makes it easy to position the mirror 21 according to the position of the workpiece point P and the dimensions of the mirror 21.

[0037] Next, a laser processing apparatus according to the third embodiment will be described with reference to Figure 7. The following description will omit explanations of components common to the laser processing apparatus according to the first embodiment, which was described with reference to Figures 1 to 5.

[0038] Figure 7 is a schematic perspective view of a laser processing apparatus according to the third embodiment. In the first embodiment (Figure 1), a laser light source 40 is connected to each of the multiple lens barrels 10. In contrast, in the third embodiment, a single energy-sharing laser light source 40 is used. Multiple laser light guide optical systems 41 are connected to the single laser light source 40, and pulsed laser beams of equal power are guided by the multiple laser light guide optical systems 41.

[0039] Next, the excellent effects of the third embodiment will be described. In the third embodiment, as in the first embodiment, the excellent effect of suppressing damage to the mirror 21 (Figure 2) is obtained. Furthermore, by using an energy-sharing laser light source 40 as in the third embodiment, the coherence of the multiple focused laser beams 15 can be increased.

[0040] Next, a laser processing apparatus according to the fourth embodiment will be described with reference to Figure 8. The following description will omit explanations of components common to the laser processing apparatus according to the first embodiment, which was described with reference to Figures 1 to 5.

[0041] Figure 8 is a schematic perspective view of a laser processing apparatus according to the fourth embodiment. In the first embodiment (Figure 2), the fluence of the laser beam required for processing is spatially divided and then focused onto a single workpiece point P. In contrast, in the fourth embodiment, the fluence of the laser beam required for processing is divided temporally.

[0042] A laser beam output from a single laser light source 40 enters the beam scanner 42 via a laser light guide optical system 41. The beam scanner 42 scans the incoming laser beam under control from the system control unit 60. For example, a galvanometer scanner is used as the beam scanner 42. A lens 43 focuses the laser beam scanned by the beam scanner 42 to form a focused laser beam 15. For example, an fθ lens is used as the lens 43. For example, the laser beam is scanned so that adjacent laser pulses on the time axis propagate through different paths of focused laser beams 15. In this case, the point where the laser beam enters the lens 43 can be considered as the output point 11 of the laser beam.

[0043] Multiple mirrors 21 (Figure 2) within the mirror box 20 reflect the focused laser beam 15 scanned by the beam scanner 42. The beam scanner 42, lens 43, and mirrors 21 are configured to focus the scanned focused laser beam 15 to a single point.

[0044] Next, we will describe the excellent effects of the fourth embodiment. In the fourth embodiment, a single pulsed laser beam is scanned, and adjacent laser pulses on the time axis are incident on different mirrors 21. Focusing on one mirror 21, the repetition frequency of the laser pulses incident on the mirror 21 is lower than the repetition frequency of the pulses of the pulsed laser beam output from the laser light source 40. As a result, the energy incident on the mirror 21 per unit time is reduced. This suppresses damage to the mirror 21.

[0045] Next, a modified laser processing apparatus according to the fourth embodiment will be described with reference to Figure 9. Figure 9 is a schematic perspective view of a modified laser processing apparatus according to the fourth embodiment. In the fourth embodiment (Figure 8), each of the multiple laser pulses of the pulsed laser beam output from the laser light source 40 is directed to one of the paths of the multiple focused laser beams 15. In contrast, in the modified apparatus shown in Figure 9, the pulse repetition frequency is high or the scanning speed of the laser beam is slow, making it impossible to clearly separate and understand the path of the focused laser beam 15 after scanning.

[0046] When the laser beam is scanned by the beam scanner 42, the focused laser beam 15 can be considered to move almost continuously in a direction perpendicular to its optical axis. One mirror 21 is positioned within the range of movement of the optical axis of the focused laser beam 15. The reflection points 22 of the focused laser beam 15 on the reflective surface of the mirror 21 trace linear trajectories corresponding to the scanning of the focused laser beam 15. The focused laser beam 15 reflected at any of the reflection points 22 is focused to a common workpiece point P.

[0047] As shown in the modified example in Figure 9, the path of the focused laser beam 15 may not be clearly separated, and the incident position of the focused laser beam 15 may move almost continuously across the reflection surface of the mirror 21.

[0048] The embodiments described above are illustrative, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. Similar effects and benefits from similar configurations in multiple embodiments will not be mentioned sequentially for each embodiment. Furthermore, the present invention is not limited to the embodiments described above. For example, it will be obvious to those skilled in the art that various modifications, improvements, and combinations are possible. [Explanation of Symbols]

[0049] 10 Telescope Tubes 11 Output locations 12 Collimating lenses 13 Focus Lens 15. Focused laser beam 20 Mirror Box 21 Mirror 22. Reflection points of the laser beam 40 Laser light sources 41 Laser light guide optics 42 Beam Scanner 43 lenses 50. Object to be processed 51 Groove 52 recess 53 Materials to be welded 60 System Control Unit 61 Robot Control Unit 62 Robot Arms

Claims

1. A lens that focuses multiple laser beams to create multiple focused laser beams, A mirror that reflects each of the aforementioned multiple converged laser beams Equipped with, A laser processing apparatus comprising multiple output points from which multiple laser beams are output, a lens, and a mirror, configured to converge the multiple converged laser beams to a common point.

2. moreover, A laser light source, A laser light guide optical system that guides the laser beam output from the laser light source to the plurality of output locations. A laser processing apparatus according to claim 1, comprising:

3. The laser processing apparatus according to claim 1 or 2, wherein the plurality of converged laser beams, after being reflected by the mirror, propagate along a common virtual plane.

4. A beam scanner that scans the incoming laser beam, A lens that focuses the laser beam scanned by the beam scanner into a focused laser beam, A mirror is positioned at the location where the converged laser beam is incident and reflects the scanned converged laser beam. Equipped with, A laser processing apparatus comprising a beam scanner, a lens, and a mirror configured to focus the scanned converged laser beam to a single point.

5. By using a lens to focus each of the multiple laser beams, multiple focused laser beams are created. A laser processing method in which each of the plurality of converged laser beams is reflected by a mirror and incident on a workpiece to perform processing, A laser processing method in which the plurality of output locations from which the plurality of laser beams are each emitted, the lens, and the mirror are configured to focus the plurality of convergent laser beams onto a common point on the surface of the workpiece.

6. Multiple mirrors are placed inside the recess of the workpiece, The laser beams emitted from multiple output points are focused into multiple focused laser beams. A laser processing method in which each of the multiple focused laser beams is reflected by the multiple mirrors and focused to a common point on the side surface of the recess for processing.

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