Optical unit for laser beam irradiation and laser processing device

Abstract

The present application aims to provide a laser beam irradiation optical unit and a laser processing device that can perform laser processing with high precision even when there is an inclination angle in the emission direction of a laser beam output from the output end of an optical fiber. To achieve the above object, a laser beam irradiation optical unit for irradiating a laser beam emitted from a laser oscillator onto an object to be processed to form a spot for laser processing includes a laser beam direction adjustment mechanism for adjusting the incident direction of the laser beam output from the output end of an optical fiber of the laser oscillator toward the irradiation track of the laser beam, and a collimator lens for making the laser beam parallel light, the laser beam direction adjustment mechanism being disposed between the laser oscillator and the collimator lens.

Description

Technical Field

[0001] This invention relates to an optical unit for laser beam irradiation and a laser processing apparatus. Background Technology

[0002] In recent years, laser beams have been widely used in the processing of various products. By using this laser beam, a small irradiation area (spot) with high energy density can be formed at the processing site, making various micro-processing operations easier. For example, it is known to be able to cut and weld metal plates.

[0003] The laser beam used for this processing is guided from a laser oscillator to a laser processing head via an optical fiber. Furthermore, this optical fiber is connected to the laser processing head via a connector. Within the laser processing head, in a laser beam irradiation optical unit, the incident laser beam is directed onto the workpiece via necessary optical elements, thus processing the workpiece.

[0004] Here, in order to irradiate the workpiece surface with a laser beam spot that has sufficient and appropriate energy intensity, the irradiation angle of the laser beam relative to the workpiece surface is preferably set to be perpendicular. However, the workpiece surface is not always perpendicular to the optical axis of the laser processing head. Therefore, Patent Document 1 proposes a laser irradiation device that controls the entire laser processing head in an inclined direction to change the trajectory of the laser beam so that the laser beam can irradiate the workpiece surface perpendicularly.

[0005] Prior art literature

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2011-60832 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] However, there exists a situation where the emission direction of the laser beam output from the output end of the optical fiber is not completely aligned with the reference optical axis determined by the structure of the output end of the optical fiber and the structure of the connector, but rather has a certain tilt angle. For example, the tilt angle of the emission direction of the laser beam output from the output end of the transmission fiber and the operating fiber relative to the reference optical axis determined by the structure of the output end of the transmission fiber and the operating fiber and the structure of the connector is less than 30 mrad (milliradians). Furthermore, the "emission direction" of the laser beam in this specification refers to the emission direction of the central portion of the laser beam that is radially output from the output end of the optical fiber. Additionally, the "tilt angle of the emission direction of the laser beam" in this specification refers to the tilt angle of the emission direction relative to the reference optical axis determined by the structure of the output end of the optical fiber supplying the laser beam and the structure of the connector.

[0010] When the laser beam emitted from the output end of such a transmission fiber or operating fiber has an angle, even if, as in Patent Document 1, an adjustment is made by using a mechanism that tilts the entire optical head to irradiate the processing area of ​​the workpiece, the inner side of the lens barrel of the laser beam irradiation optical unit within the optical head will still be irradiated by the laser beam. This can cause problems such as melting and breakage of the lens barrel material, and molten material from the lens barrel contaminating the optical elements within the laser beam irradiation optical unit. However, a specific solution to this problem has not yet been proposed.

[0011] Therefore, it is possible to solve the above problems by setting up a mechanism that shifts the entire optical system according to the tilt angle of the exit direction of the laser beam output from the output end of the transmission fiber and the operation fiber, so that the exit direction of the laser beam passes through the approximate optical center of the optical element of the laser beam irradiation optical unit. However, in this case, problems such as coma and distortion of the shape of the energy intensity distribution occur in the laser beam spot, making high-precision laser processing difficult.

[0012] The present invention was made in view of the following circumstances. Its object is to provide an optical unit for laser beam irradiation and a laser processing apparatus that can perform laser processing with high precision even if the emission direction of the laser beam output from the optical fiber output end has an angle.

[0013] Methods for solving problems

[0014] In order to solve the above problems, after in-depth research, the following optical unit for laser beam irradiation and laser processing device were conceived.

[0015] A. The optical unit for laser beam irradiation involved in this invention

[0016] The optical unit for laser beam irradiation according to the present invention is used for laser processing by irradiating a laser beam irradiated from a laser oscillator onto a workpiece to form a light spot. The unit is characterized by comprising, within the irradiation track of the laser beam from the laser oscillator to the workpiece, a laser beam direction adjustment mechanism for adjusting the incident direction of the laser beam output from the laser beam output end of the optical fiber of the laser oscillator toward the irradiation track; and a collimating lens for making the laser beam parallel light. The laser beam direction adjustment mechanism is disposed between the laser oscillator and the collimating lens.

[0017] B. The laser processing apparatus involved in this invention

[0018] The laser processing apparatus of the present invention is characterized in that it is obtained by housing the aforementioned optical unit for laser beam irradiation in the laser processing head of the laser processing apparatus.

[0019] Invention Effects

[0020] The optical unit for laser beam irradiation according to the present invention includes a laser beam direction adjustment mechanism for adjusting the incident direction of the laser beam output from the laser beam output end of the optical fiber of the laser oscillator toward the irradiation track, and a collimating lens for making the laser beam parallel light, within the irradiation track of the laser beam from the laser oscillator to the workpiece. Furthermore, the laser beam direction adjustment mechanism is disposed between the laser oscillator and the collimating lens. Therefore, the incident direction of the laser beam toward the irradiation track can be adjusted, so that even if there is an angle in the exit direction of the laser beam output from the optical fiber output end, the energy intensity distribution in the laser beam spot will not produce coma, and the shape of the energy intensity distribution will not be distorted. In addition, the laser beam direction adjustment mechanism is small and simple, and adjustment can be easily performed. Attached Figure Description

[0021] Figure 1 (a) and (b) are cross-sectional views showing the configuration of the optical elements of the optical unit for laser beam irradiation and the approximate trajectory of the laser beam.

[0022] Figure 2 (a) and (b) are schematic cross-sectional views of the fiber optic connector and the laser beam direction adjustment mechanism.

[0023] Figure 3 This is a summary diagram illustrating the rotary mechanism.

[0024] Figure 4 This is a simulation image of the light spot in the observation device before the incident direction of the laser beam toward the irradiation track is adjusted, as in Example 1.

[0025] Figure 5 This is a schematic diagram of the energy intensity on the Y-axis section of the light spot image in the observation device before the incident direction of the laser beam toward the irradiation track is adjusted, as described in Example 1.

[0026] Figure 6 This is a simulation diagram of the light spot image in the observation device after adjusting the incident direction of the laser beam toward the illumination track in Example 1.

[0027] Figure 7 This is a schematic diagram of the energy intensity on the Y-axis section of the spot image in the observation device after adjusting the incident direction of the laser beam toward the irradiation track in Example 1.

[0028] Figure 8 This is a simulation image of the light spot in the observation device before the incident direction of the laser beam toward the irradiation track is adjusted in Example 2.

[0029] Figure 9This is a schematic diagram of the energy intensity on the Y-axis section of the light spot image in the observation device before the incident direction of the laser beam toward the irradiation track is adjusted, as shown in Example 2.

[0030] Figure 10 This is a simulation diagram of the light spot image in the observation device after adjusting the incident direction of the laser beam toward the irradiation track in Example 2.

[0031] Figure 11 This is a schematic diagram of the energy intensity on the Y-axis section of the light spot image in the observation device after adjusting the incident direction of the laser beam toward the irradiation track in Embodiment 2.

[0032] Figure 12 This is a simulation of the light spot image in the observation device after the incident direction of the laser beam on the illumination track was adjusted, as in Comparative Example 1.

[0033] Figure 13 This is a schematic diagram of the energy intensity on the Y-axis section of the spot image in the observation device after the incident direction of the laser beam toward the illumination track has been adjusted in Comparative Example 1.

[0034] Explanation of reference numerals in the attached figures:

[0035] 1 Optical unit for laser beam irradiation

[0036] 10. Optical axis of the irradiation track

[0037] 11. Direction of laser beam emission

[0038] 12. The reference optical axis is determined by the structure of the output end of the optical fiber and the structure of the connector.

[0039] 15 Preferred Irradiation Tracks

[0040] 16 Irradiation track before adjustment

[0041] 21 Collimating Lens

[0042] 22 Optical elements for energy distribution control

[0043] 23 Observation Devices

[0044] 30 fiber optic

[0045] 31 Connector Section

[0046] 32 Connector Receiving Section

[0047] 33mm lens tube

[0048] 34 observation tubes

[0049] 40-turn trajectory

[0050] 50 output terminal central section

[0051] Rotation axis in the 51X direction

[0052] Rotation axis in the 52Y direction

[0053] 53. Ring-shaped fasteners

[0054] 54Y direction

[0055] 55X direction Detailed Implementation

[0056] Hereinafter, embodiments of the optical unit for laser beam irradiation and the laser processing apparatus according to the present invention will be described. Furthermore, the following description is merely one embodiment and is not intended to limit the interpretation of the following content.

[0057] A. Optical unit for laser beam irradiation

[0058] The laser beam irradiation optical unit of the present invention is used to irradiate a laser beam irradiated from a laser oscillator onto a workpiece to form a light spot for laser processing. Furthermore, within the irradiation track of the laser beam from the laser oscillator to the workpiece in this laser beam irradiation optical unit, there is a laser beam direction adjustment mechanism for adjusting the incident direction of the laser beam output from the laser beam output end of the optical fiber of the laser oscillator toward the irradiation track, and a collimating lens for making the laser beam parallel light. In addition, between the collimating lens and the workpiece, there is an energy distribution control optical element for determining the energy distribution of the laser beam in the light spot on the surface of the workpiece. In particular, the laser beam direction adjustment mechanism is characterized in that it is disposed between the laser oscillator and the collimating lens.

[0059] In addition, the “incident direction” of the laser beam toward the irradiation track in this specification refers to the direction in which the central part of the laser beam, which is radially output from the output end of the optical fiber, is incident toward the irradiation track.

[0060] The optical unit for laser beam irradiation is equipped with a laser beam direction adjustment mechanism, which allows adjustment of the incident direction of the laser beam onto the irradiation track. This ensures that even if the exit direction of the laser beam from the fiber output end has an angle, the energy intensity distribution in the laser beam spot will not produce coma or distortion. This enables high-precision laser processing. Furthermore, the laser beam direction adjustment mechanism is small and simple, and adjustments can be performed easily.

[0061] Figure 1 (a) and (b) are cross-sectional views showing the configuration of the optical elements of the laser beam irradiation optical unit 1 according to the present invention and a schematic trajectory of the laser beam. Here, Figure 1(a) shows the state where the incident direction of the laser beam on the irradiation path of the laser beam from the laser oscillator to the workpiece has not been adjusted when there is an angle in the exit direction of the laser beam. Figure 1 (b) shows the state in which the incident direction of the laser beam on the irradiation path of the laser beam from the laser oscillator to the workpiece has been adjusted when there is an angle in the exit direction of the laser beam.

[0062] In the optical unit 1 for laser beam irradiation, the following components are arranged sequentially from the laser oscillator side along the optical axis 10 of the irradiation track of the optical unit 1: a connector 31 that connects to the optical fiber 30 that guides the laser beam output from the laser oscillator; a connector receiving part 32 that fixes the connector 31 relative to the irradiation track of the laser beam; a collimating lens 21 that makes the laser beam output from the output end of the optical fiber 30 along the optical axis 11 of the laser beam parallel light; an energy distribution control optical element 22 that determines the energy distribution of the laser beam in the spot on the surface of the workpiece; and an observation device 23 that observes the observation light when adjusting the incident direction of the laser beam toward the irradiation track of the laser beam.

[0063] Furthermore, the optical element 22 for energy distribution control can also function as a collimator. In this case, it is preferable to place a condenser lens on the workpiece side of the optical element 22 for energy distribution control, which also functions as a collimating lens 21. When the optical element 22 for energy distribution control also functions as a collimator, the laser beam direction adjustment mechanism 20 in the laser beam irradiation optical unit 1 is positioned between the laser oscillator and the optical element 22 for energy distribution control.

[0064] The laser beam direction adjustment mechanism 20 consists of a connector part 31 for connecting the optical fiber 30 and a connector receiving part 32 for fixing the connector part 31 relative to the optical axis 10 of the irradiation track. With the center of the fiber core of the optical fiber 30 at the laser beam output end as the center point, at least one of the connector part 31 and the connector receiving part 32 rotates in an arc shape, thereby adjusting the incident direction of the laser beam toward the irradiation track.

[0065] The connector receiving part 32, the collimating lens 21, and the optical element 22 for energy distribution control are fixed to the lens barrel 33. Furthermore, a detachable observation tube 34 equipped with an observation device 23 is connected to the lens barrel 33. By connecting the detachable observation tube 34 equipped with the observation device 23 to the lens barrel 33, which forms the optical axis 10 of the laser beam's irradiation track, the incident direction of the laser beam onto the irradiation track can be confirmed when adjusting using the laser beam direction adjustment mechanism 20, which consists of the connector part 31 and the connector receiving part 32. Furthermore, after adjusting the incident direction of the laser beam onto the irradiation track, the observation tube 34 can be removed, and the surface of the workpiece can be positioned at the location previously occupied by the camera surface of the observation device 23, thereby enabling high-precision laser processing.

[0066] Furthermore, the optical unit 1 for laser beam irradiation can be an optical unit including a galvanometer optical system capable of moving the irradiation position of the laser towards the target position of the workpiece using a galvanometer mirror. Even with the galvanometer optical system included, the laser beam direction adjustment mechanism 20 in the optical unit 1 for laser beam irradiation is positioned between the laser oscillator and the collimating lens 21. Furthermore, the adjustment of the incident direction of the laser beam onto the irradiation track is also performed via a detachable observation tube 34 connected to the aforementioned observation device 23.

[0067] The laser beam incident from the laser oscillator onto the optical unit 1 for laser beam irradiation can be any laser beam suitable for laser processing. In particular, near-infrared laser beams with oscillation wavelengths of approximately 920–1080 nm, such as YAG lasers (wavelength 1064 nm), fiber lasers (wavelength 1070 nm), disk lasers (wavelength 1030 nm), and semiconductor lasers (wavelengths 935 nm, 940 nm, 980 nm, 940–980 nm, 940–1025 nm), are preferred.

[0068] Figure 1 The preferred irradiation track 15 in (a) refers to the irradiation track of the laser beam when the light spot on the surface of the workpiece is formed on the extension line of the optical axis 10 of the irradiation track in the laser beam irradiation optical unit 1. The laser beam passes through the preferred irradiation track 15, thereby passing through the collimating lens 21 and the energy distribution control optical element 22 symmetrically with respect to the optical axis 10 of the irradiation track. Therefore, the energy distribution of the laser beam in the light spot obtained by the energy distribution control optical element 22 is point-symmetrical with respect to the optical axis 10 of the irradiation track.

[0069] Figure 1In (a), the unadjusted irradiation track 16 represents the situation where the tilt angle in the laser beam's emission direction 11 is not 0 mrad, and the laser beam irradiates the optical elements arranged in the optical unit 1 in a state where it is not point-symmetric with respect to the optical axis 10 of the irradiation track. In this case, the energy distribution of the laser beam in the spot obtained by the energy distribution control optical element 22 will produce coma and distortion, and therefore it is non-point-symmetric with respect to the optical axis 10 of the irradiation track. When the energy distribution of the laser beam in the spot is non-point-symmetric with respect to the optical axis 10 of the irradiation track, the surface of the workpiece cannot be melted with high precision during laser beam processing.

[0070] Figure 1 (b) shows the case where the angle of inclination of the laser beam's exit direction 11 is not 0 mrad, and the laser beam direction adjustment mechanism 20 adjusts the incident direction of the laser beam toward the irradiation track to approximately align with the optical axis 10 of the irradiation track. To adjust the incident direction of the laser beam output from the output end of the optical fiber 30 toward the irradiation track to approximately align with the optical axis 10 of the irradiation track, the laser beam direction adjustment mechanism 20 rotates at least one of the connector portion 31 and the connector receiving portion 32 in an arc shape, with the center point of the fiber core of the optical fiber 30 at the laser beam output end as the center point, thereby adjusting the incident direction of the laser beam toward the irradiation track. In this way, the exit direction 11 of the laser beam output from the output end of the optical fiber 30 is adjusted to approximately align with the optical axis 10 of the irradiation track, thereby the laser beam passes through the optical elements arranged in the laser beam irradiation optical unit 1 symmetrically with respect to the optical axis 10 of the irradiation track. Therefore, the energy distribution of the laser beam in the spot obtained by the energy distribution control optical element 22 is point-symmetrically distributed with respect to the optical axis 10 of the irradiation track. The energy distribution of the laser beam in the spot is point-symmetric with respect to the optical axis 10 of the irradiation track. Therefore, in the processing using the laser beam, the surface energy of the workpiece can be melted with high precision.

[0071] Figure 2 (a) and (b) show schematic cross-sectional views of the optical fiber 30 and the laser beam direction adjustment mechanism 20. The laser beam output from the laser oscillator is guided to the laser processing head of the laser processing apparatus via the optical fiber 30. This optical fiber 30 is connected to the laser beam irradiation optical unit 1 within the laser processing head via a connector 31. At this time, as... Figure 2As shown in (a), the emission direction 11 of the laser beam output from the output end of the fiber 30 has an angle θ within a certain range relative to the reference optical axis (which coincides with the optical axis 10 of the irradiation track) determined by the structure of the output end of the fiber 30 and the connector 31. Specifically, for example, in the CW fiber laser of Wuhan Raycus Fiber Laser Technologies Co., Ltd., the optical axis angle of the laser beam output from the output end of the fiber is less than 30 mrad (milliradians) relative to the reference optical axis determined by the structure of the output end of the fiber and the connector.

[0072] As described above, the emission direction 11 of the laser beam output from the output end of the optical fiber 30 can be confirmed by connecting a detachable observation tube 34 equipped with an observation device 23 and irradiating the observation device 23 with the laser beam. Specifically, the observation device 23 is used to observe the irradiation position and energy distribution of the laser beam. Furthermore, it is preferable to reduce the intensity of the laser beam to a level that allows observation without damaging the observation device 23 before it is incident on the observation device 23. Any light-reducing element can be used as long as it reduces the intensity of the laser beam without distorting the incident light to the observation device 23.

[0073] As described above, the observation light incident on the observation device 23 can be either the laser beam used for processing or a reduced laser beam. However, it is not limited to the laser beam used for processing; it is preferable to use a guide light different from the laser beam used for processing, and an observation light for observation, also known as an aiming light. This is because the energy intensity of the observation light for observation is not at a level that would damage the observation device 23, and there is no need to reduce it.

[0074] Figure 2 (b) is a cross-sectional view showing a general outline of the laser beam output from the output end of the optical fiber 30 being adjusted in the incident direction of the irradiation track using the laser beam direction adjustment mechanism 20. Figure 2 In (b), the laser beam direction adjustment mechanism 20 is used to rotate the fiber optic cable 30 and the connector section 31 around the center of the fiber optic output end in an arc of radius r by an angle -θ1. The rotation trajectory 40 shows the trajectory of the connector section 31 rotating in an arc with radius r. That is, the reference optical axis 12, determined by the structure of the output end of the fiber optic cable 30 and the structure of the connector section 31, is in a state with an angle -θ1 relative to the optical axis 10 of the irradiation track. Through this adjustment, the emission direction 11 of the laser beam output from the output end of the fiber optic cable 30 becomes approximately aligned with the optical axis 10 of the irradiation track.

[0075] At this time, it is preferable that the laser beam direction adjustment mechanism 20 is configured to rotate in an arc shape with the center of the output end of the optical fiber 30 of the laser oscillator as the center point. This is because the laser beam direction adjustment mechanism 20 has a configuration in which at least one of the connector portion 31 and the connector receiving portion 32 rotates in an arc shape with the center of the core of the optical fiber 30 at the laser beam output end as the center point. Therefore, it is possible to adjust the incident direction of the laser beam output from the output end of the optical fiber toward the irradiation track relative to the reference optical axis 12 determined by the configuration of the output end of the optical fiber 30 and the configuration of the connector portion 31 to be approximately aligned with the optical axis 10 of the irradiation track of the laser beam of the laser beam irradiation optical unit 1.

[0076] When the energy distribution of the laser beam in the spot is ring-shaped, the laser beam direction adjustment mechanism 20 is used to adjust it so that the energy distribution of the incident light onto the observation device 23 does not become an skewed ring. When the energy distribution of the laser beam in the spot is Gaussian-shaped, the laser beam direction adjustment mechanism 20 is used to adjust it so that the energy distribution of the incident light onto the observation device 23 does not become an skewed Gaussian shape.

[0077] [Laser beam direction adjustment mechanism]

[0078] In the laser beam direction adjustment mechanism 20, the rotation angle θ of the arc-shaped rotation centered on the central part of the output end of the optical fiber 30 is preferably -40 mrad < θ < 40 mrad, assuming the direction of the optical axis 10 passing through the optical center of the optical element of the irradiation track is set to 0 mrad. This is because, since -40 mrad < θ < 40 mrad, even if there is an angle between the emission direction 11 of the laser beam output from the output end of the optical fiber 30 and the reference optical axis 12 determined by the structure of the output end of the optical fiber 30 and the connector 31, the incident direction of the laser beam in the laser beam irradiation optical unit 1 toward the irradiation track can be adjusted to be approximately aligned with the optical axis 10 of the irradiation track. On the other hand, when θ is less than -40 mrad or greater than 40 mrad, it exceeds the conventional product specifications for the angle of the emission direction 11 of the laser beam output from the output end of the optical fiber 30, thus exceeding the required specifications, and the size of the laser beam direction adjustment mechanism 20 will also increase, which is not preferred.

[0079] Furthermore, the rotation angle θ of the arc-shaped rotation with the central part of the output end of the aforementioned optical fiber 30 as the center point represents the angle in any plane along the optical axis 10 of the irradiation track and including the optical axis 10 of the irradiation track, and is not limited to the angle in a specific plane.

[0080] A specific example of the rotary mechanism of the laser beam direction adjustment mechanism 20 Figure 3 As shown. Figure 3The laser beam direction adjustment mechanism 20 shown has two rotation axes: a rotation axis 51 in the X direction 55 of the central portion 50 containing the output end of the optical fiber 30, and a rotation axis 52 in the Y direction 54 of the central portion 50 containing the output end of the optical fiber 30. Furthermore, the rotation axis 51 in the X direction 55 and the rotation axis 52 in the Y direction 54 are located in a plane orthogonal to the optical axis 10 of the irradiation direction, and are mutually orthogonal. Figure 3 In the middle, the connector part 31 is fixed by the rotation shaft 52 in the Y direction 54, and the rotation shaft 52 in the Y direction 54 is fixed by the annular fastener 53 connected to the rotation shaft 51 in the X direction 55.

[0081] At this time, the rotation angle θ of the rotation axis 51 in the X direction 55 and the rotation angle θ of the rotation axis 52 in the Y direction 54 are both set to have a range of -40 mrad < θ < 40 mrad. By using such a rotation mechanism, the rotation angle θ of the arc-shaped rotation with the central part 50 of the output end of the optical fiber 30 as the center point can be adjusted relative to the optical axis 10 of the irradiation track in any plane along and including the optical axis 10 of the irradiation track, within the range of -40 mrad < θ < 40 mrad.

[0082] However, as long as the mechanism is capable of adjusting the rotation angle θ of the arc-shaped rotation with the central portion 50 of the output end of the optical fiber 30 as the center point in any plane along and including the optical axis 10 of the irradiation track, relative to the optical axis 10 of the irradiation track, within the range of -40mrad < θ < 40mrad, the rotation mechanism is not limited to... Figure 3 The institution described.

[0083] [Observation device]

[0084] The observation device 23 is not particularly limited as long as it is capable of observing the irradiation position or energy distribution of the laser beam adjusted by the laser beam direction adjustment mechanism 20; any observation device can be used. Therefore, it is preferable that the observation tube 34 equipped with the observation device 23 can be detached from the lens tube 33. It is preferable that the position of the imaging surface of the observation device 23 when the observation tube 34 is connected to the lens tube 33 is located at the same position as the surface of the workpiece where the laser spot is formed during laser processing. Furthermore, it is preferable that the center of the imaging surface of the observation device 23 is located at the center of the processed portion of the workpiece. This is because the position and energy distribution of the laser beam can be observed at the same position as the surface of the workpiece where the laser spot is formed. Furthermore, it is because after adjusting the incident direction of the laser beam output from the output end of the optical fiber 30 toward the irradiation track to be approximately aligned with the optical axis 10 of the irradiation track, the workpiece can be processed by disassembling the observation device 23.

[0085] [Collimating lens]

[0086] Collimating lens 21 is an optical element used to make the laser beam that is output radially from the output end of optical fiber 30 parallel light.

[0087] [Optical elements for energy distribution control]

[0088] The optical element 22 for energy distribution control is an optical element that determines the energy distribution in the spot on the surface of the workpiece when a laser beam is irradiated onto the surface of the workpiece.

[0089] Here, the preferred optical element 22 for energy distribution control converts the laser beam so that the shape of the energy distribution in the spot on the surface of the workpiece is at least an annular shape consisting of an annular peripheral region. This is because, by making the shape of the energy distribution of the spot at least an annular shape consisting of an annular peripheral region, the energy of the laser beam is uniformly irradiated on the surface of the workpiece from the center region of the spot in any direction. Furthermore, this conversion allows for the removal of zinc gas during the lap welding of molten zinc steel sheets, resulting in a cleaner weld.

[0090] Furthermore, the shape of the light spot formed by the optical element 22 for energy distribution control is not particularly limited. For example, it can be a shape composed of a ring and dots at the center of the ring, or a top-hat shape, etc. In this case, it is preferable that the energy intensity of the dots at the center of the ring is higher than that of the ring portion. This is because, in materials such as aluminum with high light reflectivity, the metal can be melted in the ring portion where the energy intensity is low to reduce reflectivity, while the workpiece can be deeply melted in the center portion where the energy intensity is high, thus making laser processing easier.

[0091] To form the aforementioned spot shape, it is preferable that at least one of the effective optical surfaces of the energy distribution control optical element 22 is any one of a diffractive lens, an axial pyramidal lens, and an aspherical lens. This is because the spot shape of the laser beam can be annular, or a shape composed of an annular shape and dots in the center of the annular shape.

[0092] The optical element 22 for energy distribution control can also serve as a collimation function. When the optical element 22 for energy distribution control also serves as a collimation function, the laser beam direction adjustment mechanism 20 in the laser beam irradiation optical unit 1 is positioned between the laser oscillator and the optical element 22 for energy distribution control.

[0093] [Condensing Lens]

[0094] The workpiece side of the optical element 22 for energy distribution control can also be equipped with a focusing lens. This is because it is possible to focus a laser beam with a Gaussian shape in the energy distribution of the spot on the workpiece surface.

[0095] [Method for adjusting the incident direction of the laser beam onto the irradiation track]

[0096] The specific method for adjusting the incident direction of the laser beam onto the irradiation track using the laser beam direction adjustment mechanism 20 of the laser beam irradiation optical unit 1 will be described. Furthermore, this adjustment method is not limited to the method described below.

[0097] Here, it is assumed that the energy intensity distribution in the laser beam spot on the surface of the workpiece is annular. From the laser beam spot image captured by the observation device 23, the energy intensity distribution along the first coordinate axis, including the center of the imaging surface, is extracted. Then, with the center of the imaging surface as the origin of the first coordinate axis, the energy intensity distribution values ​​on the negative and positive sides of the first coordinate axis are integrated to obtain values ​​EM1 and EP1. Similarly, the energy intensity distribution along the second coordinate axis, which is orthogonal to the first coordinate axis, is extracted. With the center of the imaging surface as the origin of the second coordinate axis, the energy intensity distribution values ​​on the negative and positive sides of the second coordinate axis are integrated to obtain values ​​EM2 and EP2. By comparing the magnitudes of EM1, EP1, EM2, and EP2, it is possible to understand how the energy intensity of the laser beam spot image has deviated on the coordinate plane formed by the first and second coordinate axes.

[0098] Furthermore, from the laser beam spot image captured by observation device 23, the peak values ​​of energy intensity on the negative and positive sides of the first and second coordinate axes, respectively, as well as the coordinate values ​​representing the peak values, are extracted. From these peak energy intensity values ​​and the coordinate values ​​representing the peak values, the distortion state of the energy intensity distribution shape can be understood.

[0099] Based on the confirmed tilt angle information of the laser beam's emission direction, the laser beam direction adjustment mechanism 20 is used to rotate at least one of the connector section 31 and the connector receiving section 32 in an arc shape, with the center of the fiber core of the optical fiber 30 at the laser beam output end as the center point. This allows adjustment of the incident direction of the laser beam onto the irradiation track. After adjustment, the energy intensity distribution in the laser beam spot is reconfirmed using the above method. For example, based on criteria such as the difference between the magnitudes of EM1, EP1, EM2, and EP2 being within a certain allowable range, the difference between the peak values ​​of the energy intensity values ​​on the negative and positive coordinate sides being within a certain allowable range, and the difference between the absolute values ​​of the coordinate values ​​representing the peak values ​​being within a certain allowable range, it is determined that the adjustment is complete. Furthermore, if the adjustment cannot be made within the criteria after one attempt, it can be adjusted again using the above method. In this way, a suitable energy distribution can be obtained in the laser beam spot.

[0100] Furthermore, as described above, since the energy intensity distribution in the light spot can be obtained as numerical information from the observation device 23, the adjustment can also be automated by learning the above-mentioned observation values ​​obtained from the observation device 23 in advance based on the tilt angle of the laser beam's emission direction.

[0101] B. Laser processing equipment

[0102] The laser processing apparatus of the present invention is obtained by housing the aforementioned laser beam irradiation optical unit 1 in the laser processing head of the laser processing apparatus. This allows for processing of the workpiece by heating and melting it by irradiating it with a laser beam. Furthermore, the laser beam direction adjustment mechanism 20 of this laser processing apparatus can rotate at least one of the connector portion 31 and the connector receiving portion 32 in an arc shape, with the center of the fiber core of the optical fiber 30 at the laser beam output end as the center point.

[0103] Therefore, in this laser processing apparatus, even when the angle of inclination of the laser beam's exit direction 11 is not 0 mrad, the laser beam direction adjustment mechanism 20 can be used to adjust the incident direction of the laser beam onto the irradiation track to be approximately aligned with the optical axis 10 of the irradiation track. Thus, the energy distribution of the laser beam in the spot obtained by the energy distribution control optical element is point-symmetric relative to the optical axis of the irradiation track. Because the energy distribution of the laser beam in the spot is point-symmetric relative to the optical axis of the irradiation track, the surface energy of the workpiece can be melted with high precision during laser beam processing.

[0104] The embodiments of the present invention described above are one approach of the present invention, and appropriate modifications can be made without departing from the spirit of the invention. Furthermore, the following examples provide a more detailed description of the present invention, but the present invention is not limited to these examples.

[0105] [Example 1]

[0106] The adjustment result of the laser beam direction adjustment mechanism was confirmed when the output direction of the laser beam from the output end of the optical fiber was tilted at an angle of 20 mrad relative to the optical axis of the laser beam illumination track of the laser beam illumination optical unit 1. Here, the energy distribution of the laser beam in the spot obtained by the energy distribution control optical element is ring-shaped. First, the simulation result of the spot image in the observation device before adjusting the incident direction of the laser beam toward the illumination track is as follows: Figure 4 As shown. Figure 4 In the image shown, the intensity ratio when the maximum energy intensity of the laser beam is 1.0 is represented by the shades of color in the image. As shown, the emission direction of the laser beam is tilted at an angle of 20 mrad relative to the optical axis of the irradiation track. Therefore, Figure 4The image deviates from the center point of the Y-axis, and the energy intensity of the ring is non-uniform.

[0107] also, Figure 4 The energy intensity on the Y-axis cross-section of the light spot image at the center of the X-axis, such as Figure 5 As shown. According to Figure 5 It can be confirmed that the incident direction of the laser beam toward the irradiation track deviates from the optical axis (center of the Y-axis) of the irradiation track along the Y-axis, and the peak values ​​of the two energy intensities are different values.

[0108] Secondly Figure 6 It shows the use of Figure 5 The confirmed results shown, based on the positions of the two energy intensity peaks and the difference between the peaks, calculate the rotation direction and angle of the laser beam direction adjustment mechanism. The simulation results of the light spot image in the observation device are obtained by adjusting the incident direction of the laser beam onto the illumination track using the rotation of the laser beam direction adjustment mechanism. As shown in the figure, the incident direction of the laser beam onto the illumination track is approximately aligned with the optical axis of the illumination track. Figure 6 The image is located at the center point of the Y-axis and X-axis, and the energy intensity of the ring is uniform.

[0109] Next, Figure 6 The energy intensity at the center of the X-axis and on the Y-axis section of the light spot image, such as Figure 7 As shown. According to Figure 7 It can be confirmed that the incident direction of the laser beam onto the irradiation track is located on the optical axis (center of the Y-axis) of the irradiation track, and that the peak values ​​of the two energy intensities are the same. That is, the incident direction of the laser beam onto the irradiation track can be adjusted so that even if the exit direction of the laser beam from the fiber output end has an angle, the energy intensity distribution in the laser beam spot will not produce coma, and the shape of the energy intensity distribution will not be distorted. Furthermore, after adjusting the laser beam direction mechanism, the observation device is removed, and the surface of the workpiece is placed at the position previously occupied by the camera surface of the observation device, thereby confirming that the surface of the workpiece can be melted with high precision.

[0110] [Example 2]

[0111] Similar to Example 1, the adjustment result of the laser beam direction adjustment mechanism was confirmed when the laser beam's exit direction was tilted at an angle of 20 mrad relative to the optical axis of the illumination track. Here, the energy distribution of the laser beam in the spot obtained by the energy distribution control optical element exhibits a Gaussian shape. First, the simulation result of the spot image in the observation device before adjusting the incident direction towards the illumination track is as follows: Figure 8 As shown. Figure 8In the image shown, the intensity ratio when the maximum energy intensity of the laser beam is 1.0 is represented by the shades of color in the image. As shown, the emission direction of the laser beam is tilted at an angle of 20 mrad relative to the optical axis of the irradiation track. Therefore, Figure 8 The image deviates from the center point of the Y-axis.

[0112] Next, Figure 8 The energy intensity on the Y-axis cross-section of the light spot image at the center of the X-axis, such as Figure 9 As shown. According to Figure 9 It can be confirmed that the incident direction of the laser beam toward the irradiation track deviates from the optical axis (center of the Y-axis) of the irradiation track along the Y-axis.

[0113] use Figure 9 The confirmation results shown, based on information such as the deviation of the Gaussian peak position, calculate the rotation direction and angle of the laser beam direction adjustment mechanism. The simulation results of the light spot image in the observation device when adjusting the incident direction of the laser beam onto the irradiation track using the rotation of the laser beam direction adjustment mechanism are as follows: Figure 10 As shown in the figure, the incident direction of the laser beam onto the irradiation track is approximately aligned with the optical axis of the irradiation track. Figure 10 The image is located at the center point of the Y-axis and X-axis.

[0114] Next, Figure 10 The energy intensity at the center of the X-axis and on the Y-axis section of the light spot image, such as Figure 11 As shown. According to Figure 11 It can be confirmed that the incident direction of the laser beam onto the irradiation track is located on the optical axis (center of the Y-axis) of the irradiation track, and that the energy intensity distribution is Gaussian. That is, the incident direction of the laser beam onto the irradiation track can be adjusted so that even if the exit direction of the laser beam from the fiber output end has an angle, the energy intensity distribution in the laser beam spot will not produce coma, and the shape of the energy intensity distribution will not be distorted. Furthermore, after adjusting the laser beam direction mechanism, the observation device is removed, and the surface of the workpiece is placed at the position previously occupied by the camera surface of the observation device, thereby confirming that the surface of the workpiece can be melted with high precision.

[0115] Comparative example

[0116] [Comparative Example 1]

[0117] like Figure 4 , Figure 5The results of adjusting the laser beam direction without using a laser beam direction adjustment mechanism were confirmed when the laser beam's emission direction was tilted at an angle of 20 mrad relative to the optical axis of the illumination track. If the laser beam's emission direction is tilted relative to the optical axis of the illumination track, the laser beam will pass through the collimating lens and energy distribution control optical element in a non-point-symmetric state relative to their respective optical centers. Here, the collimating lens and energy distribution control optical element are shifted vertically relative to the optical axis of the illumination track so that the center of the laser beam passes approximately through the optical center of the collimating lens and energy distribution control optical element.

[0118] Simulation results of the light spot image in the observation device under the condition that the collimating lens and the optical elements for energy distribution control are shifted and adjusted in the vertical direction relative to the optical axis of the illumination track, such as... Figure 12 As shown. According to Figure 12 Although the energy intensity distribution is centered on the X and Y axes, the annular shape of the energy intensity distribution is distorted into an ellipse. Furthermore, this is in contrast to the result of adjustments made using a laser beam orientation adjustment mechanism. Figure 6 In comparison, it is obvious that the diameter of the ring is wider in both the X and Y directions.

[0119] Next, Figure 12 The energy intensity at the center of the X-axis and on the Y-axis section of the light spot image, such as Figure 13 As shown. According to Figure 13 The result of adjustment using a laser beam direction adjustment mechanism, i.e. Figure 7 In comparison, it is clear that the peak positions of the two energy intensities are far apart from the center. Even if the observation device is removed in this state, and the workpiece is placed at the position where the camera surface of the observation device was located and the laser beam is irradiated, the energy of the laser beam will not be fully focused on the surface of the workpiece, and the ring shape will be distorted. Therefore, the surface of the workpiece cannot be melted with high precision.

[0120] Industrial applicability

[0121] The optical unit for laser beam irradiation according to this invention includes a laser beam direction adjustment mechanism, which allows adjustment of the incident direction of the laser beam onto the irradiation track. This ensures that even if the exit direction of the laser beam from the fiber output end has an angle, the energy intensity distribution in the laser beam spot will not produce coma, and the shape of the energy intensity distribution will not be distorted. This enables high-precision laser processing. Furthermore, this adjustment allows for the removal of zinc gas during the lap welding of molten zinc steel sheets, resulting in clean welding. In addition, the laser beam direction adjustment mechanism is small and simple, and adjustments can be easily performed. In short, the optical unit for laser beam irradiation according to this invention is suitable for laser processing of workpieces by irradiating them with a laser beam.

Claims

1. An optical unit for laser beam irradiation, used to irradiate a workpiece with a laser beam irradiated from a laser oscillator to form a light spot for laser processing, characterized in that, Within the irradiation path of the laser beam from the laser oscillator to the workpiece, the optical unit for laser beam irradiation includes: A laser beam direction adjustment mechanism adjusts the incident direction of the laser beam output from the laser beam output end of the optical fiber of the laser oscillator toward the irradiation track; and A collimating lens is used to make the laser beam parallel light. The laser beam direction adjustment mechanism is disposed between the laser oscillator and the collimating lens. The laser beam direction adjustment mechanism consists of a connector section for connecting the optical fiber and a connector receiving section for fixing the connector section relative to the irradiation track. The laser beam direction adjustment mechanism adjusts the incident direction of the laser beam onto the irradiation track by rotating at least one of the connector portion and the connector receiving portion in an arc shape, with the center point of the fiber core at the laser beam output end as the center point. The sliding surfaces of the connector portion and the connector receiving portion during rotation are located on the spot side of the laser beam output end of the optical fiber.

2. An optical unit for laser beam irradiation, used to irradiate a workpiece with a laser beam irradiated from a laser oscillator to form a light spot for laser processing, characterized in that, Within the irradiation path of the laser beam from the laser oscillator to the workpiece, the optical unit for laser beam irradiation includes: A laser beam direction adjustment mechanism adjusts the incident direction of the laser beam output from the laser beam output end of the optical fiber of the laser oscillator toward the irradiation track; and A collimating lens is used to make the laser beam parallel light. The laser beam direction adjustment mechanism is disposed between the laser oscillator and the collimating lens. The laser beam direction adjustment mechanism consists of a connector section for connecting the optical fiber and a connector receiving section for fixing the connector section relative to the irradiation track. The laser beam direction adjustment mechanism adjusts the incident direction of the laser beam onto the irradiation track by rotating at least one of the connector portion and the connector receiving portion in an arc shape, with the center point of the fiber core at the laser beam output end as the center point. The rotation mechanism for performing the rotation has two rotation axes: an X-axis encompassing the central portion of the laser beam output end of the optical fiber and a Y-axis encompassing the central portion. These two rotation axes are located on a plane orthogonal to the optical axis of the irradiation track and are mutually orthogonal. The sliding surfaces of the connector portion and the connector receiving portion during rotation are located on the spot side of the laser beam output end of the optical fiber.

3. The optical unit for laser beam irradiation as described in claim 1 or 2, When the optical axis direction of the optical center of the optical element passing through the irradiation track is 0 mrad, the rotation angle θ of the rotation is -40 mrad < θ < 40 mrad.

4. The optical unit for laser beam irradiation as described in claim 1 or 2, The illumination track is equipped with a detachable observation device, which is used to confirm the incident direction of the laser beam onto the illumination track after adjustment using the laser beam direction adjustment mechanism.

5. The optical unit for laser beam irradiation as described in claim 4, The observation light used for observation by the observation device is a different type of observation light than the laser beam.

6. The optical unit for laser beam irradiation as described in claim 1 or 2, The irradiation track is equipped with an optical element for energy distribution control, which determines the energy distribution of the laser beam in the light spot.

7. The optical unit for laser beam irradiation as described in claim 6, The energy distribution control optical element forms a ring-shaped light spot consisting of at least a ring-shaped peripheral region as the light spot.

8. The optical unit for laser beam irradiation as described in claim 6, At least one of the effective optical surfaces of the optical element used for energy distribution control is any one of a diffractive lens, an axicon lens, and an aspherical lens.

9. A laser processing apparatus, characterized in that, The laser processing apparatus is obtained by housing an optical unit for laser beam irradiation as described in any one of claims 1 to 8 in a laser processing head.

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