Laser processing equipment

Abstract

The present invention provides a laser processing apparatus that can appropriately control the output of the laser beam according to the laser beam profile. [Solution] The profile changing unit 22 includes a mirror 23 and a piezo actuator 25. The mirror 23 reflects the laser beam LB toward the incident end of the transmission fiber 30. The piezo actuator 25 changes the angle of the mirror 23 to adjust the incident position of the laser beam LB at the incident end of the transmission fiber 30. The control unit 55 controls the operation of the laser oscillator 10 so that the output of the laser beam LB becomes smaller than a predetermined value when the angle of the mirror 23 changed by the piezo actuator 25 is within a predetermined angular range.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses an optical fiber structure in which a laser beam is directed to an incident end portion of an optical fiber having a plurality of cores, and the laser beam is made to enter a desired core, thereby changing the profile of the laser beam emitted from the optical fiber.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, depending on the profile of the laser beam, the divergence angle of the laser beam emitted from the optical fiber may increase, and there is a risk of problems occurring on the laser processing head side.

[0005] Specifically, if the divergence angle of the laser beam becomes too large, the laser beam transmitted through the optical fiber to the laser processing head may, for example, protrude radially outward beyond the collimator lens of the laser processing head, and there is a risk of ablation occurring inside the laser processing head.

[0006] The present invention has been made in view of such a point, and an object thereof is to be able to appropriately control the output of the laser light according to the profile of the laser light.

Means for Solving the Problems

[0007] The first invention is a laser processing apparatus comprising a laser oscillator that emits laser light, a transmission fiber having a plurality of cores that transmits the laser light emitted from the laser oscillator, and a control unit that controls the operation of the laser oscillator, wherein the control unit controls the laser oscillator so that the output of the laser oscillator becomes smaller than a predetermined value when the laser light is incident on different of the plurality of cores.

[0008] The second invention relates to the laser processing apparatus of the first invention, wherein the control unit stops the output of the laser oscillator when the laser light is incident on the plurality of cores.

[0009] The third invention relates to the laser processing apparatus of the first or second invention, wherein the transmission fiber comprises a first core, a second core provided on the outer periphery of the first core, and a third core provided on the outer periphery of the second core.

[0010] The fourth invention relates to the laser processing apparatus of the third invention, wherein the state in which the laser light is incident on the plurality of cores includes the state in which the laser light is incident on both the first core and the second core.

[0011] The fifth invention is a laser processing apparatus according to the first or second invention, comprising a mirror that reflects the laser light toward the incident end of the transmission fiber, and an angle changing unit that changes the angle of the mirror.

[0012] The sixth invention is a laser processing apparatus according to the fifth invention, wherein the angle changing unit is a piezo actuator. [Effects of the Invention]

[0013] According to the present invention, the output of the laser light can be appropriately controlled according to the profile of the laser light. [Brief explanation of the drawing]

[0014] [Figure 1]This is a diagram showing the overall configuration of the laser processing apparatus according to this embodiment. [Figure 2] This is a side view showing the configuration of the laser oscillator. [Figure 3] This is a front view showing the configuration of the transmission fiber. [Figure 4] This is a diagram showing the profile in a state where laser light is incident on the first core. [Figure 5] This is a diagram showing the profile in a state where laser light is incident on both the first core and the second core. [Figure 6] This is a diagram showing the profile in a state where laser light is incident on the third core. [Figure 7] This is a graph showing the relationship between the mirror tilt angle and the output NA.

Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described based on the drawings. Note that the following description of the preferred embodiments is merely illustrative in nature and is not intended to limit the present invention, its applications, or its uses.

[0016] 〈Laser Processing Apparatus〉 As shown in FIG. 1, the laser processing apparatus 1 includes a laser oscillator 10, a transmission fiber 30, a laser processing head 40, a robot 50, and a control unit 55.

[0017] The laser oscillator 10 is connected to the incident end of the transmission fiber 30. The laser processing head 40 is connected to the exit end of the transmission fiber 30. The laser light LB emitted from the laser oscillator 10 is transmitted to the laser processing head 40 via the transmission fiber 30. Details of the laser oscillator 10 and the transmission fiber 30 will be described later.

[0018] The laser processing head 40 has a collimator lens 41, a condenser lens 42, and a protective lens 43. Although not shown in the figure, the laser processing head 40 may have a parallel plate or the like for adjusting the emission position of the laser light LB.

[0019] The collimator lens 41 collimates the laser beam LB emitted from the output end of the transmission fiber 30. The condenser lens 42 condenses the laser beam LB collimated by the collimator lens 41.

[0020] The protective lens 43 is disposed at the output end of the laser processing head 40. The protective lens 43 protects against fumes and spatter generated during laser processing of the workpiece W from adhering to the optical system inside the laser processing head 40. The laser beam LB transmitted through the protective lens 43 is emitted to the workpiece W.

[0021] The laser processing head 40 is attached to the robot 50. By operating the robot 50, the laser processing head 40 can change the emission position and the focal position of the laser beam LB with respect to the workpiece W.

[0022] The control unit 55 is connected to the laser oscillator 10, the laser processing head 40, and the robot 50. The control unit 55 controls the operations of the laser oscillator 10, the laser processing head 40, and the robot 50. In addition to the moving speed of the laser processing head 40, the control unit 55 controls the start and stop of the output of the laser beam LB, the output intensity of the laser beam LB, and the like.

[0023] 〈Laser Oscillator〉 As shown in FIG. 2, the laser oscillator 10 includes a laser oscillation unit 11, an optical coupling unit 20, and a condenser unit 27.

[0024] The laser oscillation unit 11 includes a plurality of laser modules 12 and a laser beam combiner 13. The laser module 12 emits the laser beam LB. The laser beam combiner 13 combines the laser beams LB respectively emitted from the plurality of laser modules 12 and emits them as one laser beam LB.

[0025] The optical coupling unit 20 includes a folding mirror 21 and a profile changing unit 22. The folding mirror 21 reflects the laser beam LB emitted from the laser oscillation unit 11 toward the profile changing unit 22.

[0026] The profile changing unit 22 changes the profile of the laser beam LB emitted from the transmission fiber 30. The profile changing unit 22 includes a mirror 23, a piezo stage 24, and a piezo actuator 25 as an angle changing unit.

[0027] Mirror 23 reflects the laser beam LB, which has been reflected by the folded mirror 21, toward the focusing lens 28 of the focusing unit 27. The laser beam LB reflected by mirror 23 passes through the focusing lens 28 and heads toward the input end of the transmission fiber 30. Mirror 23 is integrally mounted to the piezo actuator 25.

[0028] The piezo actuator 25 is mounted on the piezo stage 24. The piezo actuator 25 adjusts the incident position of the laser beam LB at the incident end of the transmission fiber 30 by changing the angle of the mirror 23.

[0029] At the angle of mirror 23 shown by the solid line in Figure 2, the laser light LB reflected by mirror 23 is guided to the first core 31 of the transmission fiber 30. At the angle of mirror 23 shown by the dashed line in Figure 2, the laser light LB reflected by mirror 23 is guided to the second core 32 of the transmission fiber 30.

[0030] The focusing unit 27 has a focusing lens 28. The focusing lens 28 focuses the laser beam LB reflected by the mirror 23 of the profile changing unit 22 and directs it into the transmission fiber 30.

[0031] <Transmission Fiber> As shown in Figure 3, the transmission fiber 30 has a first core 31, a second core 32, a third core 33, and cladding 34.

[0032] The first core 31 is formed with a substantially circular cross-section. The material of the first core 31 is, for example, quartz glass. The second core 32 is provided on the outer periphery of the first core 31. The second core 32 is provided coaxially with the first core 31. The material of the second core 32 is, for example, quartz glass. The third core 33 is provided coaxially with the first core 31 and the second core 32. The material of the third core 33 is, for example, quartz glass.

[0033] The cladding 34 is provided on the outer periphery of the third core 33. The cladding 34 is provided coaxially with the first core 31, the second core 32, and the third core 33. The material of the cladding 34 is, for example, quartz glass.

[0034] A first low refractive index layer 35 is provided between the first core 31 and the second core 32. The first low refractive index layer 35 is made of fluorine-doped quartz glass. The refractive index of the first low refractive index layer 35 is lower than that of the first core 31 and the second core 32.

[0035] A second low refractive index layer 36 is provided between the second core 32 and the third core 33. The second low refractive index layer 36 is made of fluorine-doped quartz glass. The refractive index of the second low refractive index layer 36 is lower than that of the second core 32 and the third core 33.

[0036] A third low refractive index layer 37 is provided between the third core 33 and the cladding 34. The third low refractive index layer 37 is made of fluorine-doped quartz glass. The refractive index of the third low refractive index layer 37 is lower than that of the third core 33 and the cladding 34.

[0037] The laser beam LB is totally reflected inside at least one of the first core 31, the second core 32, and the third core 33, and is emitted from the exit end of the transmission fiber 30. Although not shown in the figure, the surface of the cladding 34 is covered with a coating.

[0038] <About the beam profile of laser light> When performing laser processing using the laser processing apparatus 1 shown in Figure 1, it is necessary to appropriately change the profile of the laser beam LB depending on the material, thickness, and processing content of the workpiece W.

[0039] In this embodiment, the incident position of the laser beam LB at the incident end of the transmission fiber 30 is adjusted by changing the angle of the mirror 23 of the profile changing unit 22 shown in Figure 2, thereby changing the beam profile of the laser beam LB emitted from the transmission fiber 30.

[0040] Specifically, in the example shown in Figure 2, the initial state is when the angle of mirror 23 is 45°, and the change in the profile of the laser beam LB when the angle of mirror 23 is changed from the initial state will be explained.

[0041] In the initial state of the mirror 23's angle as shown in Figure 2, that is, when the tilt angle of the mirror 23 is 0°, the laser beam LB is incident on the first core 31 of the transmission fiber 30, as shown in Figure 4. This mode, in which the laser beam LB is incident only on the first core 31, is called the center core mode.

[0042] In center-core mode, the beam profile of the laser light LB emitted from the transmission fiber 30 is a unimodal Gaussian distribution.

[0043] In this embodiment, "beam profile" refers to the spatial distribution of laser beam intensity. In Figure 4, the laser beam intensity is shown by the waveform change on the vertical axis, and the spatial distribution is shown by the waveform change on the horizontal axis.

[0044] From the state shown in Figure 4, if the mirror 23 is tilted further, the laser beam LB will be incident on both the first core 31 and the second core 32 of the transmission fiber 30, as shown in Figure 5. In this mode, the beam profile of the laser beam LB emitted from the transmission fiber 30 has a shape with three peaks, and the full width at half maximum of the beam profile is larger compared to the center core mode.

[0045] If the mirror 23 is tilted further from the state shown in Figure 5, the laser beam LB will be incident on the third core 33 of the transmission fiber 30, as shown in Figure 6. This mode, in which the laser beam LB is incident only on the third core 33, is called the ring core mode.

[0046] In ring-core mode, the beam profile of the laser beam LB emitted from the transmission fiber 30 has a shape with two peaks. In ring-core mode, the full width at half maximum of the beam profile is larger compared to center-core mode.

[0047] As shown in the graph in Figure 7, the output NA, which indicates the divergence angle of the laser beam LB emitted from the exit end of the transmission fiber 30, gradually increases as the tilt angle of the mirror 23 is increased, and after exceeding a predetermined peak, it tends to gradually decrease.

[0048] Specifically, at positions where the laser beam LB is incident only on the first core 31 or only on the third core 33, the laser beam LB can be emitted with a low numerical aperture (NA). On the other hand, at positions where the laser beam LB is incident across both the first core 31 and the second core 32, a portion of the laser beam LB is incident on the fluorine-doped first low refractive index layer 35 between the first core 31 and the second core 32, causing the numerical aperture (NA) of the transmission fiber 30 to deteriorate.

[0049] In this case, if the output NA is too large, the laser beam LB incident from the transmission fiber 30 to the laser processing head 40 may spill out radially outward from the collimator lens 41 of the laser processing head 40, potentially causing burnout inside the laser processing head 40.

[0050] Therefore, in this embodiment, the output of the laser beam LB is suppressed when the angle of the mirror 23 is within a predetermined angular range where the output NA of the laser beam LB is large.

[0051] Specifically, as shown in Figure 7, an acceptable numerical aperture (NA) is set for the laser processing apparatus 1 to prevent burnout inside the laser processing head 40. The angular range of the mirror 23 in which the output NA of the laser beam LB exceeds the acceptable NA is determined in advance.

[0052] The control unit 55 controls the operation of the laser oscillator 10 so that the output of the laser beam LB becomes smaller than a predetermined value when the angle of the mirror 23, which has been changed by the piezo actuator 25, is within a predetermined angular range. The predetermined value is set to an output value that can suppress burnout inside the laser processing head 40 even when the laser beam LB extends radially outward beyond the collimator lens 41 of the laser processing head 40.

[0053] Furthermore, in order to reliably prevent burnout inside the laser processing head 40, it is preferable for the control unit 55 to control the operation of the laser oscillator 10 so that the output of the laser beam LB is zero, that is, to stop the output of the laser beam LB.

[0054] Here, the predetermined angular range includes the angle of the mirror 23 into which the laser beam LB is incident on at least two of the first core 31, the second core 32, and the third core.

[0055] The control unit 55 controls the operation of the laser oscillator 10 so that the output of the laser beam LB becomes greater than a predetermined value when the angle of the mirror 23 changed by the piezo actuator 25 is the angle at which the laser beam LB is incident only on the first core 31, the angle at which the laser beam LB is incident only on the second core 32, or the angle at which the laser beam LB is incident only on the third core 33.

[0056] Specifically, when the angle of the mirror 23 is such that the laser beam LB is incident only on the first core 31, only on the second core 32, or only on the third core 33, the laser beam LB can be emitted at a low numerical aperture (NA). Therefore, even if the output of the laser beam LB is increased when starting laser processing, there is no risk of burnout occurring inside the laser processing head 40.

[0057] As described above, the laser processing apparatus 1 according to this embodiment can obtain a beam profile that corresponds to the processing content and the shape of the workpiece, and can perform laser processing of the desired quality.

[0058] For example, when cutting a thin steel plate with laser processing equipment 1, it is preferable to increase the energy density at the cutting point and to narrow the cutting width. Therefore, it is preferable to control the beam profile to a monomodal Gaussian distribution, as shown in the center core mode in Figure 4.

[0059] On the other hand, when cutting thick steel plates with the laser processing device 1, it is necessary to widen the cutting width to some extent to match the thickness of the steel plate. Therefore, it is preferable to control the beam profile to a spatially expanded shape, as shown in the ring core mode in Figure 6.

[0060] -Effects of this embodiment- In this embodiment, a laser processing apparatus comprises a laser oscillator that emits laser light and a transmission fiber having a plurality of cores that transmits the laser light emitted from the laser oscillator, the apparatus comprising a profile changing unit that changes the profile of the laser light emitted from the transmission fiber and a control unit that controls the operation of the laser oscillator, the profile changing unit comprising a mirror that reflects the laser light toward the incident end of the transmission fiber and an angle changing unit that changes the angle of the mirror to adjust the incident position of the laser light at the incident end of the transmission fiber, and the control unit controls the operation of the laser oscillator such that the output of the laser light becomes smaller than a predetermined value when the angle of the mirror changed by the angle changing unit is within a predetermined angle range.

[0061] According to the features of this embodiment, when the angle of the mirror changed by the angle changing unit is within a predetermined angle range, the operation of the laser oscillator is controlled so that the output of the laser light becomes smaller than a predetermined value, thereby allowing for appropriate control of the laser light output according to the laser light profile.

[0062] In this embodiment, the control unit controls the operation of the laser oscillator to stop the output of the laser light when the angle of the mirror changed by the angle changing unit is within a predetermined angle range.

[0063] According to the features of this embodiment, the output of the laser beam can be stopped according to the profile of the laser beam.

[0064] In this embodiment, the transmission fiber has a first core, a second core provided on the outer periphery of the first core, and a third core provided on the outer periphery of the second core, and the predetermined angular range includes the angle of the mirror into which the laser light is incident on at least two of the first core, the second core, and the third core.

[0065] According to the features of this embodiment, the output of the laser beam is suppressed when the angle of the mirror into which the laser beam is incident on at least two or more cores of the first core, second core, and third core, that is, when the divergence angle of the laser beam becomes large.

[0066] This makes it possible to suppress burnout inside the laser processing head, even if the laser beam profile has a divergence angle that extends radially outward beyond the collimator lens of the laser processing head.

[0067] In this embodiment, the control unit controls the operation of the laser oscillator so that the output of the laser light becomes greater than a predetermined value when the angle of the mirror changed by the angle changing unit is an angle at which the laser light is incident only on the first core, or an angle at which the laser light is incident only on the second core, or an angle at which the laser light is incident only on the third core.

[0068] According to the features of this embodiment, when the mirror angle is such that the laser beam is incident only on the first core, only on the second core, or only on the third core, the divergence angle of the laser beam becomes small. Therefore, even if the laser beam output is increased when starting laser processing, there is no risk of burnout occurring inside the laser processing head. [Industrial applicability]

[0069] As described above, the present invention is extremely useful and has high industrial applicability because it provides the highly practical effect of appropriately controlling the output of the laser light according to the profile of the laser light. [Explanation of symbols]

[0070] 1. Laser processing device 10. Laser Oscillator 22 Profile Change Section 23 Miller 25. Piezo actuator (angle changing section) 30 transmission fibers 31. First Core 32 Second Core 33 Third Core 55 Control Unit LB laser light

Claims

1. A laser oscillator that emits laser light, A transmission fiber having multiple cores and transmitting the laser light emitted from the laser oscillator, A control unit that controls the operation of the laser oscillator, A laser processing apparatus equipped with, The control unit controls the laser oscillator so that its output becomes less than a predetermined value when the laser light is incident on a different core among the plurality of cores. Laser processing equipment.

2. In the laser processing apparatus according to claim 1, The control unit stops the output of the laser oscillator when the laser light is incident on the plurality of cores. Laser processing equipment.

3. In the laser processing apparatus according to claim 1 or 2, The transmission fiber comprises a first core, a second core provided on the outer periphery of the first core, and a third core provided on the outer periphery of the second core. Laser processing equipment.

4. In the laser processing apparatus according to claim 3, The state in which the laser light is incident on the plurality of cores includes the state in which the laser light is incident on both the first core and the second core. Laser processing equipment.

5. In the laser processing apparatus according to claim 1 or 2, A mirror that reflects the laser light toward the incident end of the transmission fiber, The mirror comprises an angle changing unit for changing the angle of the mirror. Laser processing equipment.

6. In the laser processing apparatus of claim 5, The angle changing unit is a piezo actuator. Laser processing equipment.

Images