Laser processing system

Abstract

In a laser processing system, even if the focal point of a laser beam is shifted in the optical axis direction, it is expected that the focal point of monitoring light is always aligned with a processing site. A laser processing system is provided with: a laser beam variable focus mechanism capable of changing the focus of a laser beam on the basis of control information on the basis of three-dimensional space coordinates of a processing site; a laser beam deflection mechanism for coaxially controlling the positions of the laser beam and the monitoring light; a sensor that receives the monitoring light; a reflection part which guides the laser beam to the laser beam deflection mechanism and guides the monitoring light to the sensor; a monitoring light variable focus mechanism capable of changing the focus of the monitoring light in accordance with control information based on the three-dimensional space coordinates of the processing site; and a control unit that controls the focus of the laser beam in the laser beam variable focus mechanism on the basis of control information on the basis of the three-dimensional space coordinates of the processing site and the defocus coordinates of the laser beam, and controls the focus of the laser beam in the laser beam variable focus mechanism on the basis of control information on the basis of at least the three-dimensional space coordinates of the processing site. The focus of the monitoring light in the monitoring light variable focus mechanism is controlled.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a laser processing system. BACKGROUND

[0002] Conventionally, a laser processing system that performs welding or the like by irradiating a laser beam to a processing site of a workpiece is known. In the laser processing system, an image of a sensor is sometimes used in order to monitor the quality of the processing site of the laser beam. In a case where the processing site of the laser beam is monitored using the image of the sensor, light emitted from the processing site (hereinafter also referred to as "monitoring light") is guided to the sensor via the same optical system as an optical system for irradiating the laser beam for processing (for example, refer to Patent Literature 1).

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Laid-Open No. 2012-148315 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] According to the above-described laser processing system, even if the focal point of the laser beam is moved to another processing site, the focal point of the monitoring light can be always aligned with the focal point of the laser beam. On the other hand, in laser welding, a process of offsetting the focal point of the laser beam in the optical axis direction and heating the processing site is also performed. In the conventional laser processing system, if the focal point of the laser beam is offset in the optical axis direction, the focal point of the monitoring light is also offset in the optical axis direction. If the focal point of the monitoring light is offset in the optical axis direction, the image of the sensor becomes an image in which the focal point is blurred. Therefore, it is difficult for the operator to properly monitor the processing site of the laser beam.

[0008] Therefore, in the laser processing system, it is desirable that the focal point of the monitoring light is always aligned with the processing site even if the focal point of the laser beam is offset in the optical axis direction.

[0009] MEANS FOR SOLVING THE PROBLEMS

[0010] The laser processing system of the present disclosure is provided with: a laser beam variable focus mechanism capable of changing the focal point of a laser beam output from a laser light source in accordance with control information based on three-dimensional spatial coordinates of a processing site; a laser beam deflection mechanism that controls the position of a laser beam irradiated toward a processing site and the position of monitoring light emitted from the processing site in a coaxial manner; a sensor that receives the monitoring light; a reflection portion that reflects a laser beam emitted from the laser beam variable focus mechanism to guide the laser beam toward the laser beam deflection mechanism and transmits monitoring light emitted from the processing site to guide the monitoring light toward the sensor; a monitoring light variable focus mechanism capable of changing the focal point of the monitoring light in accordance with control information based on three-dimensional spatial coordinates of the processing site; and a control portion that generates control information for controlling the focal point of the laser beam in the laser beam variable focus mechanism, the positions of the laser beam and the monitoring light in the laser beam deflection mechanism, and the focal point of the monitoring light in the monitoring light variable focus mechanism, wherein the control portion controls the focal point of the laser beam in the laser beam variable focus mechanism in accordance with control information based on three-dimensional spatial coordinates of the processing site and a defocus coordinate of the laser beam, and the control portion controls the focal point of the monitoring light in the monitoring light variable focus mechanism in accordance with control information based on at least three-dimensional spatial coordinates of the processing site. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 is a diagram that explains the structure of the laser processing system 1 and a first irradiation method of a laser beam.

[0012] Figure 2 is a diagram that explains the focal point of three-dimensional spatial coordinates of a laser beam (defocus coordinate H = 0).

[0013] Figure 3 is a diagram that explains the focal point of three-dimensional spatial coordinates of a laser beam (defocus coordinate H ≠ 0).

[0014] Figure 4 is a diagram that explains the structure of the laser processing system 1 and a second irradiation method of a laser beam. DETAILED DESCRIPTION

[0015] An embodiment of a laser processing system related to the present disclosure will be described below. The drawings attached to the present specification are all schematic diagrams, and the shape, scale, dimensional ratio, and the like of each portion are changed or exaggerated with respect to the actual object in consideration of understanding easiness and the like.

[0016] (First Embodiment)

[0017] Figure 1 is a diagram that explains the structure of the laser processing system 1 and a first irradiation method of a laser beam. Figure 2 is a diagram that explains the focal point of three-dimensional spatial coordinates of a laser beam (defocus coordinate H = 0). Figure 3is a graph showing the focal point (defocus coordinate H≠0) of the three-dimensional spatial coordinates of the laser beam. Further, the first irradiation method of the laser beam refers to a method in which the focal point of the laser beam coincides with the processing site in the optical axis direction.

[0018] Figure 1 The laser processing system 1 illustrated is, for example, a system that performs welding or the like by irradiating a laser beam to a workpiece (object to be processed) W located on a moving stage (not illustrated). Further, the application of the laser processing system 1 is not limited to the example in which the workpiece is disposed on the moving stage, and can be appropriately changed.

[0019] As Figure 1 illustrated, the laser processing system 1 according to the embodiment includes a laser light source 10, a processing head 20, a sensor housing 30, and a control section 40.

[0020] The laser light source 10 is a device that generates a laser beam by oscillating a laser inside according to an instruction from the control section 40 (described later). As the laser light source 10, for example, a fiber laser oscillator, a pulse laser oscillator, a direct diode laser (DDL), a CO2laser oscillator, or a solid laser (YAG laser) oscillator, or the like can be used. The laser light source 10 outputs the generated laser beam to the processing head 20. Further, in Figure 1 , the path of the laser beam is indicated by a dashed line, and the path of the monitoring light is indicated by a solid line.

[0021] The processing head 20 is a device for irradiating the laser beam output from the laser light source 10 to the workpiece W from an exit (not illustrated). The processing head 20 is configured of a swing head having a swing function (described later), an electric scanning detector, and a multi-mirror. The processing head 20 includes a laser beam variable focus mechanism 21, a laser beam deflection mechanism 22, a mirror 23, a lens 24, and the like.

[0022] The laser beam variable focus mechanism 21 is a mechanism that can change the focal point of the laser beam output from the laser light source 10. The laser beam variable focus mechanism 21 controls the focal point of the laser beam according to control information based on the three-dimensional spatial coordinates X, Y, Z of the processing site and the defocus coordinate H, which is instructed from the control section 40. Specifically, the laser beam variable focus mechanism 21 adjusts the position in the optical axis direction of a lens 26 (described later) for adjusting the focal point of the laser beam based on control information related to the distance from the exit (not illustrated) of the laser beam to the processing site, so that the focal point of the laser beam is aligned with the position of the three-dimensional spatial coordinates X, Y, Z of the processing site or a position that is offset from the position by an amount corresponding to the defocus coordinate H. Further, in the present embodiment, the "optical axis direction" refers to the direction along the optical axis of the laser beam and the optical axis of the monitoring light.

[0023] The defocus coordinate (hereinafter also referred to as "defocus coordinate H") is a coordinate that indicates an amount by which the focal point of the laser beam is moved in the optical axis direction from a reference focal point determined by the three-dimensional spatial coordinates X, Y, Z. As shown in Figure 2 and Figure 3 , the reference focal point F0 of the laser beam is indicated by the three-dimensional spatial coordinates X, Y, Z. In the example shown in Figure 2 , the value of the defocus coordinate H is 0, and thus the focal point FA of the laser beam coincides with the reference focal point F0 (processing site) in the optical axis direction. On the other hand, in the example shown in Figure 3 , the defocus coordinate H is not 0 (in this example, -0.5) and thus the focal point FA of the laser beam is moved by an amount corresponding to the defocus coordinate H from the reference focal point F0 to the proximal side in the optical axis direction.

[0024] In the case where the defocus coordinate H is set to a + value, the focal point FA of the laser beam is moved to the distal side in the optical axis direction from the reference focal point F0 (not shown). On the other hand, in the case where the defocus coordinate H is set to a - value, as shown in Figure 3 , the focal point FA of the laser beam is moved to the proximal side (upper side in the figure) in the optical axis direction from the reference focal point F0. In this way, when the focal point of the laser beam is moved to the distal side or the proximal side to become a defocus state, the beam diameter of the laser beam is expanded, and thus it is possible to irradiate the laser beam to a wide area on the processing object. Setting the focal point of the laser beam to a defocus state is performed, for example, in a work in which heating is performed at a lower temperature than the heating at the time of the original welding, such as preparatory heating before welding, slow cooling after welding, and the like.

[0025] As shown in Figure 1 , the laser beam variable focal point mechanism 21 is provided with lenses 25 and 26. The lenses 25 and 26 are optical members for adjusting the focal point in the optical axis direction of the laser beam. The position in the optical axis direction of the lens 25 is fixed. The lens 26 (focal point lens) is supported so as to be movable in the position in the optical axis direction. The laser beam variable focal point mechanism 21 is provided with a ball screw, a motor, or the like (not shown) as a mechanism for moving the position of the lens 26 in the optical axis direction. The ball screw is a linear motion mechanism that converts the rotational motion of the motor to linear motion. By controlling the position in the optical axis direction of the lens 26 using this linear motion mechanism, it is possible to move the focal point of the laser beam in the optical axis direction.

[0026] Furthermore, the lens whose position is moved in the optical axis direction is not limited to the lens 26, but can also be the lens 25, and it is also possible to relatively move both of the lenses 25 and 26. In addition, as the mechanism for moving the focal point of the laser beam in the optical axis direction, it is not limited to the ball screw, and for example, a linear motion mechanism based on a linear guide rail, a mechanism that changes the focal point by moving the position of a mirror (concave mirror), a mechanism that changes the focal point by changing the shape of a lens, or the like can be used.

[0027] In general welding work, the value of the defocus coordinate H is 0, and thus the focal point of the laser beam is the reference focal point F0. On the other hand, in work in which the laser beam is made to be in a defocus state, the focal point moves in the direction of the optical axis of the laser beam in accordance with the value of the defocus coordinate H. Thus, with respect to the focal point of the laser beam, the point after the reference focal point F0 deviates to the distal side or the proximal side becomes the focal point FA.

[0028] The laser beam deflection mechanism 22 is a device that controls the focal points of the laser beam A irradiated toward the workpiece and the monitoring light B emitted from the workpiece in a coaxial manner. The laser beam deflection mechanism 22 controls the mirrors 27 and 28 (described later) in accordance with instructions from the control section 40. Specifically, the laser beam deflection mechanism 22 adjusts the rotation angles of the respective mirrors (described later) that cause the laser beam and the monitoring light to scan in accordance with control information based on the two-dimensional spatial coordinates X, Y of the workpiece indicated from the control section 40, so that the position of the laser beam A irradiated toward the workpiece and the position of the monitoring light B emitted from the workpiece become the two-dimensional spatial coordinates X, Y, respectively. Further, in the drawing, the positions of the laser beam A and the monitoring light B are illustrated as being offset from each other for the sake of easy understanding of the relationship between the laser beam A irradiated toward the workpiece and the monitoring light B emitted from the workpiece, but the laser beam A and the monitoring light B are coaxial. Figure 1

[0029] The laser beam deflection mechanism 22 has the mirrors 27 and 28. The mirrors 27 and 28 are optical members that reflect the laser beam and the monitoring light. In addition, the laser beam deflection mechanism 22 has a drive mechanism (not shown) that rotates the mirrors 27 and 28 about their respective rotation axes. The rotation angles of the mirrors 27 and 28 are controlled by the respective drive mechanisms of the mirrors 27 and 28, whereby the laser beam is scanned in two dimensions on the workpiece W. When the laser beam is irradiated from the laser beam deflection mechanism 22 toward the workpiece W, the monitoring light emitted from the workpiece passes through the same optical path as the laser beam from the laser beam deflection mechanism 22 to the sensor 31 (described later). Further, in the machining head 20, the position of the exit port E (refer to FIG. 2) of the laser beam deflection mechanism 22, which becomes the outlet of the laser beam, is fixed. Figure 2 Figure 3

[0030] The mirror (reflection portion) 23 is an optical member that reflects the laser beam emitted from the laser beam deflection mechanism 22 to guide the laser beam toward the laser beam variable focal point mechanism 21 and transmits the monitoring light emitted from the workpiece. The mirror 23 is composed of a dichroic mirror that reflects light of a specific wavelength and transmits light of other wavelengths. The lens 24 is an optical member that converges the laser beam reflected by the mirror 23 and the monitoring light emitted from the laser beam deflection mechanism 22.

[0031] ​​​The sensor housing 30 is a device that guides the monitoring light emitted from the processing area to the sensor 31. The sensor housing 30 includes the sensor 31, the monitoring light variable focus mechanism 32, and the reflector 33.

[0032] Sensor 31 is a device that receives monitoring light and generates an image of the machined area of ​​workpiece W. As the sensor 31 used in monitoring laser welding, a camera, photodiode (PD), etc., are employed. For example, a camera is used to monitor the state of the pinhole and molten pool by receiving infrared light emitted from the welding area during laser welding. A photodiode is used, for example, to receive infrared light emitted from the welding area during laser welding and estimate the temperature of the welding area based on the emitted light. Additionally, a photodiode is also used, for example, to receive visible light emitted from the welding area during laser welding to observe the presence or absence of plasma light generated when welding is defective.

[0033] The monitor light variable focus mechanism 32 is a mechanism capable of changing the focus of the monitor light. The monitor light variable focus mechanism 32 controls the focus of the monitor light based on control information from the control unit 40, which is based on the three-dimensional spatial coordinates X, Y, and Z of the processing part. Specifically, the monitor light variable focus mechanism 32 is based on the focus of the monitor light from the laser beam exit port E (refer to...). Figure 2 / Figure 3 The control information related to the distance to the processing part is used to adjust the position of the lens 34 (described later) in the optical axis direction for adjusting the focus of the monitoring light, so that the focus of the monitoring light is aligned with the three-dimensional spatial coordinates X, Y, Z of the processing part.

[0034] like Figure 1 As shown, the monitor light variable focus mechanism 32 includes a lens 34. The lens 34 (focal lens) is an optical component used to adjust the focus of the monitor light. The lens 34 is supported in a manner that allows its position to move freely in the optical axis direction. The monitor light variable focus mechanism 32 includes a ball screw, a motor, etc. (not shown) as mechanisms for moving the position of the lens 34 in the optical axis direction. The ball screw is a linear motion mechanism that converts the rotational motion of the motor into linear motion. By using this linear motion mechanism to control the position of the lens 34 in the upper optical axis direction, the focus of the monitor light can be moved in the optical axis direction.

[0035] Furthermore, the mechanism for moving the focal point of the monitoring light along the optical axis is not limited to a ball screw. For example, a linear motion mechanism based on a linear guide, a mechanism for changing the focal point by moving the position of a mirror (concave mirror), or a mechanism for changing the focal point by changing the shape of a lens can be used.

[0036] The control information of the three-dimensional spatial coordinates X, Y, Z based on the machining site instructed from the control section 40 to the monitoring light variable focus mechanism 32 is the same as the control information of the three-dimensional spatial coordinates X, Y, Z based on the machining site instructed from the control section 40 to the laser beam variable focus mechanism 21. Therefore, in the first irradiation method of the laser beam (described later), the focus of the three-dimensional spatial coordinates of the monitoring light and the focus of the three-dimensional spatial coordinates of the laser beam are coincident at the machining site. On the other hand, in the monitoring light variable focus mechanism 32, the control of the focus based on the defocus coordinate H is not performed, and therefore, in the second irradiation method of the laser beam (described later), the focus of the three-dimensional spatial coordinates of the monitoring light also coincides with the machining site.

[0037] The mirror 33 is an optical member for making the monitoring light that has passed through the mirror (reflection section) 23 enter the monitoring light variable focus mechanism 32.

[0038] The control section 40 controls the focus of the laser beam in the laser beam variable focus mechanism 21, the positions of the laser beam and the monitoring light in the laser beam deflection mechanism 22, and the focus of the monitoring light in the monitoring light variable focus mechanism 32. Specifically, the control section 40 controls the position in the optical axis direction of the lens for adjusting the focus of the laser beam by transmitting control information based on the three-dimensional spatial coordinates X, Y, Z and the defocus coordinate H of the machining site as an instruction to the laser beam variable focus mechanism 21. In addition, the control section 40 controls the rotation angle of the mirror that causes the laser beam and the monitoring light to scan in the two-dimensional space by transmitting control information based on the two-dimensional spatial coordinates X, Y of the machining site as an instruction to the laser beam deflection mechanism 22. Furthermore, the control section 40 controls the position in the optical axis direction of the lens for adjusting the focus of the monitoring light by transmitting control information based on the three-dimensional spatial coordinates X, Y, Z of the machining site as an instruction to the monitoring light variable focus mechanism 32.

[0039] Furthermore, in the instructions transmitted from the control section 40 to the laser beam variable focus mechanism 21, the laser beam deflection mechanism 22, and the monitoring light variable focus mechanism 32, in addition to the control information described above, a speed instruction for instructing the moving speed of the lens, the mirror, and the like can also be included. In the laser beam variable focus mechanism 21, the laser beam deflection mechanism 22, and the monitoring light variable focus mechanism 32, the moving speed of the lens, the mirror, and the like is set based on the speed instruction from the control section 40.

[0040] The control section 40 is constituted by, for example, a computer provided with a memory such as a ROM, a RAM, a CPU, and a communication control section. The control section 40 cooperates with each hardware to execute various functions by appropriately reading out and executing an operating system (OS) and various application programs stored in an external memory. Further, the control section 40 can be constituted by a CNC (Computer Numerical Controller), a PLC (Programmable Logic Controller), or the like, or can be connected to a higher-level computer that outputs a machining condition in addition to a machining program.

[0041] Next, the first irradiation method and the second irradiation method of the laser beam in the laser processing system 1 will be described with reference to Figures 1 to 3 and Figure 4 Figure 4 is a view that explains the structure of the laser processing system 1 and the second irradiation method of the laser beam. Further, the second irradiation method of the laser beam refers to a method in which the focal point of the laser beam is shifted in the optical axis direction from the processing site.

[0042] In the first irradiation method, the control section 40 transmits control information based on the three-dimensional spatial coordinates X, Y, Z of the processing site and the defocus coordinate H (H = 0) as an instruction to the laser beam variable focus mechanism 21. In the first irradiation method, the value of the defocus coordinate H is 0, and thus in the laser beam variable focus mechanism 21, control to move the focal point of the laser beam in the optical axis direction from the reference focal point F0 is not performed. In the first irradiation method, in the laser beam variable focus mechanism 21, control is performed in accordance with the control information instructed from the control section 40 so that the focal point of the laser beam coincides with the three-dimensional spatial coordinates X, Y, Z.

[0043] In the first irradiation method, the control section 40 transmits control information based on the two-dimensional spatial coordinates X, Y of the processing site as an instruction to the laser beam deflection mechanism 22. Thereby, in the laser beam deflection mechanism 22, the position of the laser beam in the two-dimensional space is controlled so as to coincide with the processing site. In addition, in the first irradiation method, the control section 40 transmits control information based on the three-dimensional spatial coordinates X, Y, Z of the processing site as an instruction to the monitoring light variable focus mechanism 32. Thereby, in the monitoring light variable focus mechanism 32, the focal point of the monitoring light is controlled to coincide with the processing site.

[0044] As shown in Figure 1 , in the first irradiation method, the focal point FA of the laser beam A coincides with the focal point FB of the monitoring light B at the reference focal point F0 (processing site). In the first irradiation method, the focal point of the monitoring light coincides with the focal point of the laser beam, and thus the operator can monitor the quality of the processing site of the laser beam through the focused image.​

[0045] In the second irradiation mode, the control unit 40 sends control information based on the three-dimensional spatial coordinates X, Y, Z of the processing location and the defocus coordinate H as instructions for the laser beam variable focus mechanism 21. Here, an example of moving the laser beam focus from the processing location towards the proximal side will be described. When the laser beam focus is moved from the processing location towards the proximal side, the defocus coordinate H is a negative value. In the second irradiation mode, in the laser beam variable focus mechanism 21, the laser beam focus is controlled according to the instructions sent from the control unit 40, so that the laser beam focus moves from a position consistent with the three-dimensional spatial coordinates X, Y, Z towards the proximal side by an amount corresponding to the defocus coordinate H (negative value).

[0046] In the second irradiation mode, the control unit 40 sends the two-dimensional spatial coordinates X and Y of the processing area as instructions to the laser beam deflection mechanism 22. Thus, the laser beam deflection mechanism 22 controls the two-dimensional spatial position of the laser beam in a manner that aligns the focal point of the laser beam with the processing area. Additionally, in the second irradiation mode, the control unit 40 sends the three-dimensional spatial coordinates X, Y, and Z of the processing area as instructions to the monitor light variable focus mechanism 32. Thus, the monitor light variable focus mechanism 32 controls the position of the monitor light along its optical axis in a manner that aligns the focal point of the monitor light with the processing area.

[0047] like Figure 4 As shown, in the second irradiation mode, the focal point of the laser beam moves from the reference focal point F0 (processing area) to the proximal side by an amount corresponding to the defocus coordinate H. On the other hand, the focal point of the monitoring light coincides with the processing area. In the second irradiation mode, regardless of where the focal point of the laser beam moves in the optical axis direction, the focal point of the monitoring light coincides with the reference focal point F0. Therefore, in the sensor 31, even during the operation of heating the processing area by shifting the focal point of the laser beam in the optical axis direction, a focused image as an image of the processing area of ​​the laser beam can be generated.

[0048] As explained above, the laser processing system 1 according to the first embodiment can keep the focus of the monitoring light aligned with the processing area even when the focus of the laser beam is shifted in the optical axis direction. Therefore, the operator can monitor the quality of the laser-processed area by the focused image even when performing a heating operation by shifting the focus of the laser beam in the optical axis direction.

[0049] (Second Implementation)

[0050] The wavelengths of the laser beam for laser welding and the monitoring light for monitoring the processing site are different from each other. For example, the wavelength of the laser beam is 1070 nm, and the wavelength of the monitoring light is 400 nm to 600 nm, 800 nm to 900 nm, or 1300 nm to 1500 nm. In this way, if the wavelengths of the light used are different, the refractive indexes with respect to the lens also differ, and thus the focal points of the laser beam and the monitoring light can not coincide even if the same control information is transmitted from the control section 40.

[0051] In a case where a ball screw is used as the linear motion mechanism of the laser beam variable focal point mechanism 21 and the monitoring light variable focal point mechanism 32, the control information of the lens based on the three-dimensional spatial coordinates is the rotation angle of the motor calculated by the following equation (1).

[0052] Rotation angle of motor = (target position x first conversion coefficient) + second conversion coefficient (1)

[0053] Here, the target position is the focal point position (X, Y, Z or X, Y, Z, H) of the laser beam. The first conversion coefficient is a coefficient for calculating the rotation angle of the motor required to move the lens to the target position. The first conversion coefficient differs depending on the specifications (styles) of the lens. The second conversion coefficient is a coefficient for correcting the set position of the lens, the reference focal point F0, and the position of the focal point FB.

[0054] In a case where the specifications of the lens for adjusting the focal point of the laser beam and the specifications of the lens for adjusting the focal point of the monitoring light are different, the control section 40 sets the first conversion coefficient in accordance with the respective specifications of the lenses. In addition, in a case where the specifications of the lens for adjusting the focal point of the laser beam and the specifications of the lens for adjusting the focal point of the monitoring light are the same or the optical characteristics are similar, the control section 40 sets the value of the first conversion coefficient in accordance with the specifications of the lens, and sets the value of the second conversion coefficient in accordance with the respective wavelengths of the laser beam and the monitoring light.

[0055] According to the second embodiment, the focal points of the laser beam and the monitoring light can be made to coincide even in a case where the wavelengths of the laser beam and the monitoring light are different from each other. Thus, the focal point of the monitoring light can be more appropriately aligned even in a case where the wavelengths of the light used differ depending on the specifications of the sensor.

[0056] (Third Embodiment)

[0057] In laser welding, sometimes welding is performed by a method called oscillation. Oscillation is a method in which welding is performed while the position of the focal point of the laser beam is moved at high speed. In laser welding by oscillation, the speed command is faster than usual, and therefore in the laser beam variable focus mechanism 21, the lens 26 is moved at high speed. On the other hand, in the monitoring light variable focus mechanism 32, even if the movement of the monitoring light is not made to follow the movement of the laser beam, no problem occurs in the case of monitoring the machining site. Therefore, as in laser welding based on oscillation, in the case where the speed command is a value equal to or higher than a predetermined value, the speed command transmitted from the control section 40 to the monitoring light variable focus mechanism 32 is made relatively smaller than the speed command transmitted to the laser beam deflection mechanism 22. Thereby, it is possible to extend the life of the ball screw that is a direct drive mechanism constituting the monitoring light variable focus mechanism 32, and therefore it is possible to make the system operate more stably.

[0058] (Modification)

[0059] The embodiments of the present disclosure have been described above, but the present disclosure is not limited to the above-described embodiments. The embodiments can be variously added, replaced, changed, partially deleted, or the like within a range not departing from the gist of the present disclosure or within a range not departing from the gist of the present disclosure derived by the content recited by the claims and equivalents thereof. In addition, the embodiments can be implemented in combination. For example, in the above-described embodiments, the order of each action, the order of each process is shown as one example, and is not limited to these orders.

[0060] In the embodiments, an example in which the focal point of the monitoring light is controlled in the monitoring light variable focus mechanism 32 in accordance with control information based on the three-dimensional spatial coordinates X, Y, Z of the machining site has been described, but is not limited thereto. In the monitoring light variable focus mechanism 32, the focal point of the monitoring light can also be controlled in accordance with control information based on the three-dimensional spatial coordinates X, Y, Z of the machining site and the defocus coordinate H.

[0061] In the embodiments, an example in which the focal point of the laser beam and the focal point of the monitoring light are controlled in the laser beam deflection mechanism 22 in a coaxial manner in accordance with control information based on the two-dimensional spatial coordinates X, Y of the machining site has been described, but is not limited thereto. In the laser beam deflection mechanism 22, the focal point of the laser beam and the focal point of the monitoring light can also be controlled in a coaxial manner in accordance with control information based on the three-dimensional spatial coordinates X, Y, Z of the machining site.

[0062] With respect to the above-described embodiments, the following supplementary notes are further disclosed.

[0063] (Supplementary Note 1)

[0064] A laser processing system includes: a laser beam variable focus mechanism (21) capable of changing a focal point of a laser beam output from a laser light source according to control information based on three-dimensional spatial coordinates of a processing site; a laser beam deflection mechanism (22) that controls a position of the laser beam irradiated toward the processing site and a position of monitoring light emitted from the processing site in a coaxial manner; a sensor (31) that receives the monitoring light; a reflecting portion (23) that reflects the laser beam emitted from the laser beam variable focus mechanism to guide the laser beam toward the laser beam deflection mechanism and transmits the monitoring light emitted from the processing site to guide the monitoring light toward the sensor; a monitoring light variable focus mechanism (32) capable of changing a focal point of the monitoring light according to control information based on three-dimensional spatial coordinates of the processing site; and a control portion (40) for controlling the focal point of the laser beam in the laser beam variable focus mechanism, the positions of the laser beam and the monitoring light in the laser beam deflection mechanism, and the focal point of the monitoring light in the monitoring light variable focus mechanism, wherein the control portion controls the focal point of the laser beam in the laser beam variable focus mechanism according to control information based on three-dimensional spatial coordinates of the processing site and a defocus coordinate of the laser beam, and controls the focal point of the monitoring light in the monitoring light variable focus mechanism according to control information based on at least the three-dimensional spatial coordinates of the processing site.

[0065] (Addendum 2)

[0066] The control portion (40) sets a conversion coefficient for adjusting the focal point of the laser beam in the control of the laser beam variable focus mechanism (21) and a conversion coefficient for controlling the focal point of the monitoring light in the control of the monitoring light variable focus mechanism to different values.

[0067] (Addendum 3)

[0068] In a case where a speed command for the laser beam variable focus mechanism (21) is a value or more than a predetermined value, the control portion (40) relatively makes a speed command for the monitoring light variable focus mechanism (32) smaller than the speed command for the laser beam variable focus mechanism.

[0069] Explanation of Reference Numerals

[0070] 1: laser processing system; 10: laser light source; 20: processing head; 21: laser beam variable focus mechanism; 22: laser beam deflection mechanism; 23: mirror (reflecting portion); 30: sensor housing; 31: sensor; 32: monitoring light variable focus mechanism; 40: control portion.

Claims

1. A laser processing system comprising: a laser beam variable focus mechanism capable of changing a focal point of a laser beam output from a laser light source in accordance with control information based on three-dimensional spatial coordinates of a processing site; a laser beam deflection mechanism that controls a position of the laser beam irradiated toward the processing site and a position of monitoring light emitted from the processing site in a coaxial manner; a sensor that receives the monitoring light; a reflecting portion that reflects the laser beam emitted from the laser beam variable focus mechanism to guide the laser beam toward the laser beam deflection mechanism, and transmits the monitoring light emitted from the processing site to guide the monitoring light toward the sensor; a monitoring light variable focus mechanism capable of changing a focal point of the monitoring light in accordance with control information based on three-dimensional spatial coordinates of the processing site; and a control portion that generates control information for controlling the focal point of the laser beam in the laser beam variable focus mechanism, the positions of the laser beam and the monitoring light in the laser beam deflection mechanism, and the focal point of the monitoring light in the monitoring light variable focus mechanism, the control portion controls the focal point of the laser beam in the laser beam variable focus mechanism in accordance with control information based on three-dimensional spatial coordinates of the processing site and a defocus coordinate of the laser beam, the control portion controls the focal point of the monitoring light in the monitoring light variable focus mechanism in accordance with control information based on at least the three-dimensional spatial coordinates of the processing site.

2. The laser processing system according to claim 1, wherein the control portion sets a conversion factor for adjusting the focal point of the laser beam in the control of the laser beam variable focus mechanism and a conversion factor for controlling the focal point of the monitoring light in the control of the monitoring light variable focus mechanism to different values.

3. The laser processing system according to claim 1 or 2, wherein in a case where a speed command for the laser beam variable focus mechanism is a value or more than a predetermined value, the control portion relatively makes a speed command for the monitoring light variable focus mechanism smaller than the speed command for the laser beam variable focus mechanism. ​ ​ ​ ​ wherein ​ ​ ​ ​ ​ ​

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