Laser processing head

Abstract

To change a beam profile of a laser beam emitted to a workpiece in a laser processing head.SOLUTION: A laser processing head 20 includes: an aspheric lens 21; a collimator lens 22; and a focus lens 23. A first movement mechanism 31 moves the aspheric lens 21 in an optical axis direction. A second movement mechanism 32 moves the collimator lens 22 in the optical axis direction. The aspheric lens 21 and the collimator lens 22 are moved in the optical axis direction to change a beam profile of the laser beam L emitted to a workpiece W.SELECTED DRAWING: Figure 1

Description

Technical Field

[0006] , ,

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

Background Art

[0002] Patent Document 1 discloses a laser processing machine configured to transmit laser light emitted from a laser oscillator to a coupler through a feeding fiber, and transmit the laser light with a changed beam profile at the coupler to a processing head through a process 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, in the invention of Patent Document 1, in order to change the beam profile of the laser light, it is necessary to change the configurations of the laser oscillator and the transmission fiber, which increases the cost. Further, when changing the beam profile of the laser light, since the numerical aperture (NA) of the transmission fiber increases, there is a problem that the optical system of the laser processing head has to be enlarged.

[0005] The present invention has been made in view of such points, and an object thereof is to change the beam profile of the laser light emitted to a workpiece within a laser processing head.

Means for Solving the Problems

[0006] The first invention is a laser processing head that emits laser light to a workpiece, comprising: a transmission fiber for transmitting the laser light; a focusing lens for focusing the laser light transmitted by the transmission fiber; at least one aspherical lens arranged in the optical path of the laser light; and a moving mechanism for moving the aspherical lens in the optical axis direction to change the beam profile of the laser light emitted to the workpiece.

[0007] In the first invention, spherical aberration is generated by moving an aspherical lens, which is placed in the optical path of the laser beam, along the optical axis. This makes it possible to change the beam profile of the laser beam emitted towards the workpiece within the laser processing head while keeping the beam profile of the laser beam incident from the transmission fiber constant.

[0008] In this way, there is no need to change the configuration of the laser oscillator or transmission fiber in order to change the beam profile of the laser light. Furthermore, by keeping the numerical aperture (NA) of the transmission fiber constant, there is no need to increase the diameter of the optical system of the laser processing head, thus preventing the laser processing head from becoming larger.

[0009] The second invention is a laser processing head of the first invention, wherein at least one of the aspherical lenses is positioned on the transmission fiber side of the focus lens.

[0010] In the second invention, by placing an aspherical lens on the transmission fiber side of the focus lens and moving the aspherical lens toward the workpiece, a beam profile can be obtained in which the outer periphery of the circular laser beam is surrounded by a ring-shaped laser beam.

[0011] This allows the workpiece to be preheated with a ring-shaped laser beam, and then processed with a circular laser beam.

[0012] Furthermore, by placing the aspherical lens on the transmission fiber side, the diameter of the aspherical lens can be reduced and the overall length of the head can be shortened compared to when the aspherical lens is placed on the workpiece side.

[0013] The third invention is a laser processing head of the first or second invention, wherein the aspherical lens positioned closest to the transmission fiber satisfies the condition that the focal length f is f > |200| mm.

[0014] In the third invention, the beam profile can be changed while maintaining a small minimum spot diameter.

[0015] The fourth invention relates to a laser processing head of any one of the first to third inventions, wherein the aspherical lens has negative power that diverges the laser light.

[0016] In the fourth invention, the laser light diverged by the aspherical lens is focused by the focusing lens and emitted onto the workpiece. This shifts the focusing position of the peripheral portion of the beam towards the workpiece, generating aberrations and changing the beam profile of the laser light.

[0017] The fifth invention is a laser processing head of the first invention, wherein at least one of the aspherical lenses is positioned on the workpiece side of the focusing lens.

[0018] In the fifth invention, by placing an aspherical lens on the workpiece side of the focusing lens and moving the aspherical lens toward the workpiece to generate spherical aberration, a beam profile can be obtained in which the outer edge of the circular laser beam is surrounded by a ring-shaped laser beam.

[0019] This allows the workpiece to be preheated with a ring-shaped laser beam, and then processed with a circular laser beam. [Effects of the Invention]

[0020] According to the present invention, within a laser processing head, the beam profile of the laser light emitted to a workpiece can be changed.

Brief Description of the Drawings

[0021] [Figure 1] It is a schematic diagram showing the configuration of the laser processing apparatus according to Embodiment 1. [Figure 2] It is a diagram showing the positions of an aspherical lens, a collimator lens, and a focus lens for obtaining a first beam profile. [Figure 3] It is a diagram showing a first beam profile. [Figure 4] It is a diagram showing the positions of an aspherical lens, a collimator lens, and a focus lens for obtaining a second beam profile. [Figure 5] It is a diagram showing a second beam profile. [Figure 6] It is a diagram showing the positions of an aspherical lens, a collimator lens, and a focus lens for obtaining a third beam profile. [Figure 7] It is a diagram showing a third beam profile. [Figure 8] It is a diagram for comparing the sizes of the minimum spot diameters due to the differences in the focal lengths of the aspherical lenses. [Figure 9] It is a schematic diagram showing the configuration of the laser processing apparatus according to Embodiment 2. [Figure 10] It is a diagram showing the positions of an aspherical lens, a collimator lens, and a focus lens for obtaining a first beam profile. [Figure 11] It is a diagram showing a first beam profile. [Figure 12] It is a diagram showing the positions of an aspherical lens, a collimator lens, and a focus lens for obtaining a second beam profile. [Figure 13] It is a diagram showing a second beam profile. [Figure 14]This figure shows the positions of the aspherical lens, collimator lens, and focusing lens for obtaining the third beam profile. [Figure 15] This is a diagram showing the third beam profile. [Modes for carrying out the invention]

[0022] Embodiments of the present invention will be described below with reference to the drawings. The following description of preferred embodiments is essentially illustrative and is not intended to limit the present invention, its applications, or its uses.

[0023] Embodiment 1 As shown in Figure 1, the laser processing apparatus 1 comprises a laser oscillator 10, a transmission fiber 15, a laser processing head 20, a first moving mechanism 31, a second moving mechanism 32, and a control unit 35.

[0024] The laser oscillator 10 outputs laser light L. The laser light L output from the laser oscillator 10 is injected into the transmission fiber 15.

[0025] The input end of the transmission fiber 15 is connected to the laser oscillator 10. The output end of the transmission fiber 15 is connected to the laser processing head 20. The transmission fiber 15 transmits the laser light L incident from the laser oscillator 10 toward the laser processing head 20.

[0026] The laser processing head 20 emits the laser beam L transmitted through the transmission fiber 15 toward the outside. In the laser processing apparatus 1 shown in Figure 1, the laser beam L is emitted toward the workpiece W placed at a predetermined position.

[0027] The laser processing head 20 includes an aspherical lens 21, a collimator lens 22, a focusing lens 23, and protective glass 24. The aspherical lens 21, collimator lens 22, focusing lens 23, and protective glass 24 are arranged in the optical path of the laser beam L in order from the upstream side in the direction of emission of the laser beam L.

[0028] The aspherical lens 21 has negative power that diverges the laser beam L. Specifically, the aspherical lens 21 has a concave surface 21a. The aspherical lens 21 is positioned so that the concave surface 21a faces downstream in the direction of emission of the laser beam L. The aspherical lens 21 diverges the laser beam L emitted from the output end of the transmission fiber 15.

[0029] Here, by positioning the aspherical lens 21 closer to the transmission fiber 15 than the focus lens 23, the diameter of the aspherical lens can be reduced and the overall length of the head can be shortened compared to when the aspherical lens 21 is positioned closer to the workpiece W.

[0030] The collimator lens 22 parallelizes the laser beam L that was diverged by the aspherical lens 21.

[0031] The focus lens 23 focuses the laser beam L that has been parallelized by the collimator lens 22. The laser beam L focused by the focus lens 23 passes through the protective glass 24 and is emitted to the workpiece W.

[0032] The protective glass 24 is placed between the workpiece W and the focus lens 23. The protective glass 24 protects the focus lens 23 from fumes and spatter generated during laser processing of the workpiece W, preventing them from adhering to the focus lens 23.

[0033] The first moving mechanism 31 moves the aspherical lens 21 in the optical axis direction. The first moving mechanism 31 is composed of, for example, an actuator combining a motor and a cam. However, the first moving mechanism 31 is not limited to this form and only needs to be configured to move the aspherical lens 21 in the optical axis direction.

[0034] The second movement mechanism 32 moves the collimator lens 22, which acts as an aspherical lens, in the optical axis direction. The second movement mechanism 32 is composed of, for example, an actuator combining a motor and a cam. However, the second movement mechanism 32 is not limited to this form and only needs to be configured to move the collimator lens 22 in the optical axis direction.

[0035] The control unit 35 is connected to the laser oscillator 10, the first moving mechanism 31, and the second moving mechanism 32. The control unit 35 controls the output of the laser beam L from the laser oscillator 10. The control unit 35 controls the operation of the first moving mechanism 31 and the second moving mechanism 32.

[0036] Furthermore, the control unit 35 may control the operation of a manipulator (not shown) to which the laser processing head 20 is attached.

[0037] <Modification of beam profile> In the laser processing head 20 according to this embodiment 1, the beam profile of the laser light L incident from the transmission fiber 15 is kept constant, while the beam profile of the laser light L emitted towards the workpiece W is changed within the laser processing head 20.

[0038] Specifically, the beam profile of the laser beam L is changed by altering the optical axis positions of the aspherical lens 21 and the collimator lens 22.

[0039] The following describes how to change the beam profile of the laser beam L to a first beam profile (see Figures 2 and 3), a second beam profile (see Figures 4 and 5), or a third beam profile (see Figures 6 and 7) depending on the positions of the aspherical lens 21 and the collimator lens 22.

[0040] At the optical axis positions of the aspherical lens 21 and collimator lens 22 shown in Figure 2, a circular first beam profile can be obtained as shown in Figure 3. In Figure 3, the minimum spot diameter of the laser beam L is small and the light intensity at the center of the laser beam L is high, making it suitable for processing the workpiece W.

[0041] Next, as shown in Figure 4, the optical axis positions of the aspherical lens 21 and the collimator lens 22 are moved toward the workpiece W. In the example shown in Figure 4, the aspherical lens 21 is moved 0.146 mm toward the workpiece W from its position in Figure 2. The collimator lens 22 is also moved 0.036 mm toward the workpiece W from its position in Figure 2. By moving the aspherical lens 21 and the collimator lens 22 toward the optical axis in this way and generating spherical aberration, the second beam profile shown in Figure 5 can be obtained. Note that the amount of movement of the aspherical lens 21 and the collimator lens 22 is merely an example and is not limited to this.

[0042] Here, as shown in Figure 5, the second beam profile has a shape in which the outer periphery of the circular laser beam L is surrounded by a ring-shaped laser beam L. This allows the workpiece W to be preheated with the ring-shaped laser beam L, and then processed with the circular laser beam L.

[0043] Next, as shown in Figure 6, the optical axis positions of the aspherical lens 21 and the collimator lens 22 are further moved toward the workpiece W. In the example shown in Figure 6, the aspherical lens 21 is moved 0.2 mm toward the workpiece W from its position in Figure 2. The collimator lens 22 is also moved 0.047 mm toward the workpiece W from its position in Figure 2. By moving the aspherical lens 21 and the collimator lens 22 toward the optical axis in this way and generating spherical aberration, the third beam profile shown in Figure 7 can be obtained. Note that the amount of movement of the aspherical lens 21 and the collimator lens 22 is merely an example and is not limited to this.

[0044] Here, as shown in Figure 7, the third beam profile has a shape in which the outer periphery of the circular laser beam L is surrounded by a ring-shaped laser beam L. In the third beam profile, the outer diameter of the ring-shaped laser beam L is larger compared to the second beam profile (see Figure 5).

[0045] This allows the workpiece W to be preheated over a wide area with a ring-shaped laser beam L, and then processed with a circular laser beam L, compared to when the laser beam L is emitted with a second beam profile.

[0046] <Regarding the focal length of aspherical lenses> As shown in Figure 2, the distance between the output end of the transmission fiber 15 and the surface of the aspherical lens 21 facing the transmission fiber 15 is defined as the focal length f of the aspherical lens 21. Here, since the minimum spot diameter of the laser beam L differs depending on the difference in the focal length f of the aspherical lens 21, it is necessary to set it to an appropriate dimension.

[0047] Specifically, as shown in Figure 8, in the laser processing head 20 according to this embodiment, the focal length of the aspherical lens 21 is set to f = -284.8 mm. On the other hand, in the comparative example, the focal length of the aspherical lens 21 is set to f = -150 mm. Then, in Figure 8, the spherical aberration of the first beam profile in which the laser beam L is circular is compared between this embodiment and the comparative example.

[0048] In Figure 8, it can be seen that in the comparative example's laser beam L beam profile, aberration occurs when the laser beam L is reduced to its minimum spot diameter, resulting in a larger spot diameter compared to the laser beam L beam profile of this embodiment.

[0049] Therefore, in this embodiment, in order to change the beam profile while maintaining a small minimum spot diameter, the focal length of the aspherical lens 21 is set to satisfy the condition f > |200| mm.

[0050] -Effects of Embodiment 1- As described above, the laser processing head 20 according to this embodiment 1 generates spherical aberration by moving the aspherical lens 21 and the collimator lens 22 in the optical axis direction. This makes it possible to change the beam profile of the laser light L emitted towards the workpiece W within the laser processing head 20 while keeping the beam profile of the laser light L incident from the transmission fiber 15 constant.

[0051] In this way, there is no need to change the configuration of the laser oscillator 10 or the transmission fiber 15 in order to change the beam profile of the laser light L. Furthermore, by keeping the numerical aperture (NA) of the transmission fiber 15 constant, there is no need to increase the diameter of the optical system of the laser processing head 20, and the size of the laser processing head 20 can be kept down.

[0052] Embodiment 2 In the following description, the same reference numerals are used for parts that are the same as those in Embodiment 1, and only the differences will be described.

[0053] As shown in Figure 9, the laser processing head 20 includes a collimator lens 22, a focus lens 23, an aspherical lens 21, and protective glass 24. The collimator lens 22, focus lens 23, aspherical lens 21, and protective glass 24 are arranged in the optical path of the laser beam L in order from the upstream side in the direction of emission of the laser beam L.

[0054] The collimator lens 22 parallelizes the laser light L incident from the transmission fiber 15.

[0055] The focusing lens 23 focuses the laser beam L that has been parallelized by the collimator lens 22. The laser beam L focused by the focusing lens 23 passes through the aspherical lens 21.

[0056] The aspherical lens 21 is positioned closer to the workpiece W than the focusing lens 23. The aspherical lens 21 is positioned so that its concave surface 21a faces upstream in the direction of laser beam L emission. The laser beam L that passes through the aspherical lens 21 passes through the protective glass 24 and is emitted to the workpiece W.

[0057] The protective glass 24 is placed between the workpiece W and the aspherical lens 21. The protective glass 24 protects the aspherical lens 21 and the focusing lens 23 from fumes and spatter generated during laser processing of the workpiece W, preventing them from adhering to the aspherical lens 21 and the focusing lens 23.

[0058] The first movement mechanism 31 moves the aspherical lens 21 in the optical axis direction.

[0059] The third movement mechanism 33 moves the focus lens 23, which is an aspherical lens, in the optical axis direction. The third movement mechanism 33 is composed of, for example, an actuator combining a motor and a cam. However, the third movement mechanism 33 is not limited to this form and only needs to be configured to move the focus lens 23 in the optical axis direction.

[0060] The control unit 35 is connected to the laser oscillator 10, the first moving mechanism 31, and the third moving mechanism 33. The control unit 35 controls the operation of the first moving mechanism 31 and the third moving mechanism 33.

[0061] <Modification of beam profile> In the laser processing head 20 according to this second embodiment, the beam profile of the laser beam L is changed by changing the position of the aspherical lens 21 and the focus lens 23 in the optical axis direction.

[0062] The following describes how to change the beam profile of the laser beam L to a first beam profile (see Figures 10 and 11), a second beam profile (see Figures 12 and 13), or a third beam profile (see Figures 14 and 15) depending on the position of the aspherical lens 21 and the focus lens 23.

[0063] At the optical axis positions of the aspherical lens 21 and the focusing lens 23 shown in Figure 10, a circular first beam profile can be obtained as shown in Figure 11. In Figure 11, the minimum spot diameter of the laser beam L is small and the light intensity at the center of the laser beam L is high, making it suitable for processing the workpiece W.

[0064] Next, as shown in Figure 12, the optical axis positions of the aspherical lens 21 and the focusing lens 23 are moved toward the workpiece W. In the example shown in Figure 12, the aspherical lens 21 is moved 0.103 mm toward the workpiece W from its position in Figure 10. The focusing lens 23 is also moved 0.02 mm toward the workpiece W from its position in Figure 10. By moving the aspherical lens 21 and the focusing lens 23 toward the workpiece W in this way and generating spherical aberration, the second beam profile shown in Figure 13 can be obtained. Note that the amount of movement of the aspherical lens 21 and the focusing lens 23 is merely an example and is not limited to this.

[0065] Here, as shown in Figure 13, the second beam profile has a shape in which the outer periphery of the circular laser beam L is surrounded by a ring-shaped laser beam L. This allows the workpiece W to be preheated with the ring-shaped laser beam L, and then processed with the circular laser beam L.

[0066] Next, as shown in Figure 14, the optical axis positions of the aspherical lens 21 and the focusing lens 23 are further moved toward the workpiece W. In the example shown in Figure 14, the aspherical lens 21 is moved 0.152 mm toward the workpiece W from its position in Figure 10. The focusing lens 23 is also moved 0.037 mm toward the workpiece W from its position in Figure 10. By moving the aspherical lens 21 and the focusing lens 23 toward the workpiece W in this way and generating spherical aberration, the third beam profile shown in Figure 15 can be obtained. Note that the amount of movement of the aspherical lens 21 and the focusing lens 23 is merely an example and is not limited to this.

[0067] Here, as shown in Figure 15, the third beam profile has a shape in which the outer periphery of the circular laser beam L is surrounded by a ring-shaped laser beam L. In the third beam profile, the outer diameter of the ring-shaped laser beam L is larger than that of the second beam profile (see Figure 13).

[0068] This allows the workpiece W to be preheated over a wide area with a ring-shaped laser beam L, and then processed with a circular laser beam L, compared to when the laser beam L is emitted with a second beam profile.

[0069] -Effects of Embodiment 2- As described above, with the laser processing head 20 according to this second embodiment, by arranging the aspherical lens 21 on the workpiece W side of the focus lens 23 and moving the aspherical lens 21 toward the workpiece W side to generate spherical aberration, a beam profile can be obtained in which the outer periphery of the circular laser beam L is surrounded by a ring-shaped laser beam L.

[0070] This allows the workpiece W to be preheated with a ring-shaped laser beam L, and then processed with a circular laser beam L. [Industrial applicability]

[0071] As described above, the present invention is extremely useful and has high industrial applicability because it provides the highly practical effect of being able to change the beam profile of the laser light emitted towards the workpiece within the laser processing head. [Explanation of symbols]

[0072] 15 Transmission Fiber 20 Laser processing heads 21 Aspherical lenses 23 Focus Lens 31 1st movement mechanism 32 Second movement mechanism 33 Third movement mechanism Double job L Laser light

Claims

1. A laser processing head that emits laser light onto a workpiece, A transmission fiber for transmitting the aforementioned laser light, A focusing lens for focusing the laser light transmitted through the transmission fiber, A collimator lens positioned on the optical path of the laser light, on the transmission fiber side of the focus lens, An aspherical lens, which is positioned on the optical path of the laser beam on the transmission fiber side of the focus lens and the collimator lens, and is configured separately from the focus lens and the collimator lens, The system includes a moving mechanism that moves the aspherical lens and the collimator lens in the direction of the optical axis, thereby changing the beam profile of the laser beam emitted towards the workpiece to a beam profile in which the outer circumference of the circular laser beam is surrounded by a ring-shaped portion of the laser beam. Laser processing head.

2. A laser processing head that emits laser light onto a workpiece, A transmission fiber for transmitting the aforementioned laser light, A focusing lens for focusing the laser light transmitted through the transmission fiber, An aspherical lens, which is positioned on the optical path of the laser beam closer to the workpiece than the focusing lens and is configured separately from the focusing lens, The system includes a moving mechanism that moves the aspherical lens and the focusing lens in the direction of the optical axis, thereby changing the beam profile of the laser beam emitted towards the workpiece to a beam profile in which the outer circumference of the circular laser beam is surrounded by a ring-shaped portion of the laser beam. Laser processing head.

3. In the laser processing head according to claim 1 or 2, The aspherical lens positioned closest to the transmission fiber has a focal length f, f > | 200 | mm The conditions are met Laser processing head.

4. In any one of the laser processing heads according to claim 1 to 3, The aspherical lens has negative power that diverges the laser light. Laser processing head.

5. In the laser processing head of Claim 1, The moving mechanism includes a first moving mechanism for moving the aspherical lens in the optical axis direction and a second moving mechanism for moving the collimator lens in the optical axis direction. Laser processing head.

6. In the laser processing head of claim 2, The aforementioned moving mechanism includes a first moving mechanism for moving the aspherical lens in the optical axis direction and a third moving mechanism for moving the focusing lens in the optical axis direction. Laser processing head.

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