Laser processing machine and method for correcting focused beam diameter of laser processing machine

Abstract

To suppress deterioration in processing quality due to adhesion of pollutant on a protective glass.SOLUTION: A laser beam machine comprises: a focal position changing part which changes a relative position between a focal position of a laser beam oscillated by a laser oscillator and penetrating through a lens and a work-piece by changing a relative position between the lens and the work-piece; a protective glass which is arranged on a laser beam path between the lens and the work-piece; a storage part which stores, when pollutant is adhered to the protective glass, a relation between a deviation amount of the focal position of the laser beam and a condensing diameter at a position at a prescribed distance from the focal position; a deviation amount acquisition part which acquires a current deviation amount at the focal position of the laser beam; a condensing diameter estimation part which estimates a current condensing diameter at the position of the laser beam based on the current deviation amount acquired by the deviation amount acquisition part and the relation stored in the storage part; and a calibration execution part which controls the focal position changing part through the current deviation amount and the current condensing diameter to calibrate the current condensing diameter.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present disclosure relates to a laser processing machine and a method for correcting a focused beam diameter of the laser processing machine. [Background technology]

[0002] Patent Document 1 describes a technique for correcting the shift in focal position caused by the thermal lens effect in a laser processing machine. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 07-051875 Summary of the Invention [Problem to be solved by the invention]

[0004] Dust from fumes or sputters generated during laser processing may adhere to the protective glass provided on the laser head. If the laser head emits laser light with dust on the protective glass, the laser light is scattered by the dust, the diameter of the focused spot at the processing point increases, and the processing quality deteriorates. Therefore, the deterioration of the processing quality cannot be sufficiently suppressed by simply correcting the shift in the focal position due to the thermal lens effect, as in the technology described in Patent Document 1. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms.

[0006] (1) According to a first embodiment of the present disclosure, there is provided a laser processing machine, which includes: a focal position changing unit that changes a focal position of a laser beam oscillated from a laser oscillator and transmitted through the lens with respect to a surface of the workpiece by changing a relative position between a lens and a workpiece; a protective glass disposed on a path of the laser beam between the lens and the workpiece; a storage unit that stores in advance a relationship between a deviation amount of the focal position of the laser beam from a target position when a contaminant adheres to the protective glass and a focused beam diameter of the laser beam on the surface of the workpiece; a deviation amount acquiring unit that acquires a current deviation amount of the focal position of the laser beam from the target position; a focused beam diameter estimating unit that estimates a current focused beam diameter of the laser beam on the surface of the workpiece using the current deviation amount acquired by the deviation amount acquiring unit and the relationship stored in the storage unit; and a correction executing unit that corrects the current focused beam diameter by controlling the focal position changing unit using the current deviation amount acquired by the deviation amount acquiring unit and the current focused beam diameter estimated by the focused beam diameter estimating unit. According to the laser processing machine of this aspect, it is possible to correct the change in the focused diameter at the processing point caused by the adhesion of contaminants to the protective lens, thereby suppressing the deterioration of the processing quality of the laser processing by the laser processing machine. (2) In the laser processing machine of the above aspect, the relationship may represent that the focused beam diameter increases as the amount of deviation in a direction from the workpiece toward the lens increases. With this type of laser processing machine, the greater the degree of contamination of the protective glass, the greater the shift in the focal position away from the workpiece due to the thermal lens effect, and the greater the degree of contamination of the protective glass, the greater the focal diameter due to the scattering of laser light. By utilizing this phenomenon, the focal diameter can be appropriately corrected. (3) In the laser processing machine of the above aspect, the correction execution unit may correct the current focused diameter by moving the focal position by a sum of a first movement amount for moving the focal position so that the current deviation amount becomes zero, and a second movement amount for further moving the focal position from the position where the current deviation amount becomes zero so that the focused diameter on the surface of the workpiece becomes a target diameter. According to the laser processing machine of this aspect, the focal diameter of the laser beam can be corrected by moving the focal position once, without moving the focal position of the laser beam twice, and therefore the correction of the focal diameter of the laser beam can be completed in a short time. (4) The laser processing machine of the above-described embodiment may include a light receiving element that receives the laser light reflected by the workpiece, and the deviation amount acquisition unit may acquire the current deviation amount using the intensity of the laser light measured by the light receiving element. According to the laser processing machine of this aspect, the current deviation amount of the focal position of the laser light can be obtained automatically. (5) According to a second embodiment of the present disclosure, there is provided a method for correcting a focal diameter of a laser processing machine having a protective glass for protecting a lens. The method for correcting a focal diameter of a laser processing machine includes: a deviation amount acquisition step of acquiring a current deviation amount from a target position of the focal position of a laser beam transmitted through the lens and the protective glass and irradiated onto a surface of a workpiece; a focal diameter estimation step of estimating a current focal diameter of the laser beam on the surface of the workpiece using the current deviation amount acquired in the deviation amount acquisition step, a deviation amount of the focal position of the laser beam from the target position when a contaminant adheres to the protective glass, which is previously acquired, and a relationship between the focal diameter of the laser beam on the surface of the workpiece and the focal diameter of the laser beam; and a correction execution step of correcting the current focal diameter by changing a relative position between the lens and the workpiece using the current deviation amount acquired in the deviation amount acquisition step and the current focal diameter estimated in the focal diameter estimation step. According to the focal position correction method for a laser processing machine of this aspect, it is possible to correct the change in the focused diameter at the processing point caused by the adhesion of contaminants to the protective lens, thereby suppressing the deterioration of the processing quality of the laser processing by the laser processing machine. The present disclosure may be realized in various forms other than the laser processing machine and the method for correcting the focused diameter of the laser processing machine. For example, the present disclosure may be realized in the form of a laser processing method. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is an explanatory diagram illustrating a schematic configuration of a laser processing machine. [Diagram 2] FIG. 11 is an explanatory diagram showing the relationship between time and the intensity of return light when the focal position is moved. [Diagram 3] FIG. 4 is an explanatory diagram showing how laser light is scattered by contaminants attached to a protective glass. [Figure 4] 1 is a first graph showing the relationship between the focus shift amount and the focused light diameter. [Diagram 5] 11 is a second graph showing the relationship between the focus shift amount and the focused light diameter. [Figure 6] 11 is a third graph showing the relationship between the focus shift amount and the focused light diameter. [Figure 7] FIG. 4 is an explanatory diagram showing the contents of a table. [Figure 8] 11 is a flowchart showing the content of a light collection diameter correction process. [Figure 9] 6A and 6B are explanatory diagrams illustrating a state in which a light-collection diameter is corrected by a light-collection diameter correction process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A. First embodiment: FIG. 1 is an explanatory diagram showing a schematic configuration of a laser processing machine 10 in the first embodiment. The laser processing machine 10 processes a workpiece WK using a laser light LS. Processing using the laser light LS includes, for example, welding, cutting, and drilling. In this embodiment, the laser processing machine 10 is configured to perform welding on the workpiece WK. Note that in other embodiments, the laser processing machine 10 may be configured to perform cutting or drilling on the workpiece WK instead of welding on the workpiece WK.

[0009] In this embodiment, the laser processing machine 10 includes a laser oscillator 100, a laser head 200, a head support portion 300, a stage 400, and a control device 500. A workpiece WK is fixed to the stage 400.

[0010] The laser oscillator 100 generates a laser light LS. In this embodiment, the laser light LS generated by the laser oscillator 100 is a fiber laser. Note that in other embodiments, the laser light LS generated by the laser oscillator 100 may be a solid-state laser other than a fiber laser, such as a disk laser, a semiconductor laser, or a YAG laser. The laser light LS generated by the laser oscillator 100 may be a gas laser, such as a carbon dioxide laser, instead of a solid-state laser.

[0011] The laser oscillator 100 is connected to the laser head 200 by an optical fiber 150. The laser light LS generated by the laser oscillator 100 is transmitted from the laser oscillator 100 to the laser head 200 by the optical fiber 150. When the laser light LS generated by the laser oscillator 100 is a carbon dioxide laser, it is preferable that the laser light LS is transmitted from the laser oscillator 100 to the laser head 200 by a bend mirror, not the optical fiber 150.

[0012] The laser head 200 includes a collimating lens 210, a dichroic mirror 220, a first reflecting mirror 230, a focal position changing unit 240, a second reflecting mirror 250, a condensing lens 260, an irradiation position changing unit 270, and a protective glass 280. The laser light LS introduced from the optical fiber 150 to the laser head 200 is converted into parallel light by the collimating lens 210, reflected by the dichroic mirror 220 toward the first reflecting mirror 230, and reflected by the first reflecting mirror 230 toward the focal position changing unit 240. The laser light LS that passes through the focal position changing unit 240 is reflected by the second reflecting mirror 250 toward the condensing lens 260. The laser light LS condensed by the condensing lens 260 is guided to the protective glass 280 by the irradiation position changing unit 270, and is emitted toward the workpiece WK through the protective glass 280. In FIG. 1, the path of the above-mentioned laser light LS is indicated by a solid line.

[0013] The focal position changing unit 240 includes a Z lens 241 and a Z lens driving unit 242. The Z lens 241 is disposed on the path of the laser light LS between the first reflecting mirror 230 and the second reflecting mirror 250. In FIG. 1, arrows are shown representing three mutually orthogonal coordinate axes, namely, X, Y, and Z axes. The X and Y axes are coordinate axes parallel to the horizontal plane, and the Z axis is a coordinate axis parallel to the vertical direction. The Z lens driving unit 242 changes the position of the Z lens 241 along the path of the laser light LS, thereby changing the focal position of the laser light LS on the Z axis. For example, an electric linear actuator can be used as the Z lens driving unit 242.

[0014] The irradiation position changing section 270 includes an X mirror 271, an X mirror driving unit 272, a Y mirror 276, and a Y mirror driving unit 277. The X mirror 271 and the Y mirror 276 are disposed on the path of the laser light LS between the condenser lens 260 and the protective glass 280. The X mirror driving unit 272 changes the direction of the X mirror 271 to change the irradiation position of the laser light LS on the workpiece WK in the X axis. The Y mirror driving unit 277 changes the direction of the Y mirror 276 to change the irradiation position of the laser light LS on the workpiece WK in the Y axis. For example, a motor can be used for the X mirror driving unit 272 and the Y mirror driving unit 277.

[0015] The protective glass 280 is disposed on the path of the laser light LS between the irradiation position changing unit 270 and the workpiece WK. The protective glass 280 protects various components provided in the laser head 200, such as the condenser lens 260, the X mirror 271, and the Y mirror 276, from fumes and spatters generated during welding. In this embodiment, the protective glass 280 is made of quartz glass on which an anti-reflection film is formed.

[0016] The laser head 200 is equipped with a return light detection device 290. The return light detection device 290 includes a third reflection mirror 291 and a light receiving element 292. A part of the laser light LS emitted from the laser head 200 is reflected on the surface of the workpiece WK and returns to the laser head 200. In the following description, the laser light LS returning to the laser head 200 is referred to as return light. The return light introduced into the laser head 200 through the protective glass 280 passes through the irradiation position change unit 270, the condenser lens 260, the second reflection mirror 250, the focal position change unit 240, and the first reflection mirror 230 in this order, and is guided to the dichroic mirror 220. The return light passes through the dichroic mirror 220 and is introduced into the return light detection device 290. The third reflection mirror 291 reflects the return light introduced into the return light detection device 290 toward the light receiving element 292. The light receiving element 292 receives the returning light and outputs an electrical signal representing the intensity of the returning light. The electrical signal output from the light receiving element 292 is transmitted to the control device 500. In Fig. 1, the path of the returning light described above is indicated by a two-dot chain line.

[0017] The head support part 300 supports the laser head 200. In this embodiment, the head support part 300 has a function of changing the irradiation position of the laser light LS on the workpiece WK by changing the position of the laser head 200. In this embodiment, the head support part 300 is configured with a robot arm. Note that, in other embodiments, the head support part 300 may be configured with a fixing jig that does not have a function of changing the position of the laser head 200.

[0018] The control device 500 is configured by a computer including a CPU 501, a memory 502, an input / output interface 503, and an internal bus 504 that interconnects these. In this embodiment, the control device 500 controls the laser oscillator 100, the Z lens driving unit 242 of the focal position changing section 240, the X mirror driving unit 272 and the Y mirror driving unit 277 of the irradiation position changing section 270, and the head support section 300. The memory 502 may be referred to as a storage section.

[0019] In this embodiment, the control device 500 has a processing execution unit 510, an inspection execution unit 520, a deviation amount acquisition unit 530, a focused diameter estimation unit 540, and a correction execution unit 550. The processing execution unit 510, the inspection execution unit 520, the deviation amount acquisition unit 530, the focused diameter estimation unit 540, and the correction execution unit 550 are realized in software by the CPU 501 executing a computer program stored in the memory 502. Note that the control device 500 may be configured by a combination of multiple circuits instead of a computer.

[0020] The processing execution unit 510 performs welding processing of the workpiece WK by irradiating the workpiece WK with the laser light LS from the laser head 200. The processing execution unit 510 controls the focal position change unit 240 to adjust the focal position of the laser light LS to a predetermined target position and the focused diameter of the laser light LS on the surface of the workpiece WK to a predetermined target diameter. The processing execution unit 510 performs welding processing on the workpiece WK while moving the irradiation position of the laser light LS on the workpiece WK by controlling the irradiation position change unit 270. The processing execution unit 510 controls the focal position change unit 240 so that the focal position of the laser light LS is located on the laser head 200 side with respect to the surface of the workpiece WK. The processing execution unit 510 starts welding processing after the temperature of optical elements such as the condenser lens 260 provided in the laser head 200 has stabilized.

[0021] The inspection execution unit 520 irradiates the workpiece WK with a laser beam LS having a lower output than that during processing from the laser head 200, and inspects the welding quality of the workpiece WK using the intensity of the returned light measured by the light receiving element 292 of the returned light detection device 290. Specifically, the inspection execution unit 520 compares the waveform of the intensity of the returned light measured by the light receiving element 292 with a reference waveform pre-stored in the memory 502 to determine whether the welding quality of the workpiece WK is good or bad. The reference waveform can be the waveform of the intensity of the returned light obtained by irradiating a good product with a low-output laser beam LS from the laser head 200.

[0022] The deviation amount acquisition unit 530 acquires the deviation amount of the focal position of the laser light LS from the target position by using the return light detection device 290. In the following description, the deviation amount of the focal position from the target position is called the focus shift amount. The focus shift amount becomes a positive value when the focal position is deviated in the direction from the workpiece WK to the laser head 200, and becomes a negative value when the focal position is deviated in the direction from the workpiece WK to the laser head 200. A method for acquiring the focus shift amount will be described later. The beam diameter estimation unit 540 estimates the current beam diameter by using the current focus shift amount acquired by the deviation amount acquisition unit 530 and a table TB representing the relationship between the focus shift amount and the beam diameter of the laser light LS stored in advance in the memory 502. The correction execution unit 550 executes correction of the current beam diameter of the laser light LS in the beam diameter correction process.

[0023] FIG. 2 is an explanatory diagram showing the relationship between time and the intensity of the return light when the focal position F is moved at a constant speed. In FIG. 2, the horizontal axis represents time, and the vertical axis represents the intensity of the return light. A method for acquiring the focus shift amount in this embodiment will be described with reference to FIG. 2. First, the deviation amount acquisition unit 530 irradiates a low-power laser light LS from the laser head 200 toward the workpiece WK, and measures the intensity of the return light by the light receiving element 292 of the return light detection device 290 while changing the distance between the focal position F of the laser light LS and the workpiece WK at a constant speed by the focal position change unit 240. In the following description, the distance between the focal position F of the laser light LS and the surface of the workpiece WK is called the defocus amount. When the defocus amount is negative, the focal position F is located on the stage 400 side with respect to the surface of the workpiece WK, and when the defocus amount is positive, the focal position F is located on the laser head 200 side with respect to the surface of the workpiece WK. The smaller the absolute value of the defocus amount, the greater the intensity of the return light, and when the defocus amount is zero, the intensity of the return light is maximum. Next, the shift amount acquisition unit 530 calculates the difference Δt between the time until a peak in the intensity of the return light appears in the waveform Wm of the intensity of the return light measured when the focal position F is moved at a constant speed so that the defocus amount changes from negative to positive, and the time until a peak in the intensity of the return light appears in the reference waveform Wb of the intensity of the return light pre-stored in the memory 502 of the control device 500, and acquires the amount of focus shift by multiplying the difference Δt by the moving speed of the focal position F.

[0024] FIG. 3 is an explanatory diagram showing a state in which the laser light LS is scattered by the contaminant M attached to the protective glass 280. The contaminant M may adhere to the surface of the protective glass 280. The contaminant M is, for example, dust derived from fumes or sputters generated during processing. When the contaminant M adheres to the surface of the protective glass 280, the laser light LS is scattered by the contaminant M, and the focused diameter of the laser light LS at the processing point on the surface of the workpiece WK becomes large. Furthermore, the contaminant M is heated by the laser light LS, the temperature of the protective glass 280 increases, and the focal position F of the laser light LS shifts toward the laser head 200 due to the thermal lens effect of the protective glass 280. Therefore, when the contaminant M adheres to the surface of the protective glass 280, not only the scattering of the laser light LS but also the thermal lens effect changes the focused diameter of the laser light LS at the processing point. If the focused diameter of the laser light LS at the processing point changes, the energy density of the laser light LS at the processing point changes, which may result in a decrease in processing quality and inspection accuracy. Therefore, in this embodiment, the control device 500 corrects the focused light diameter at the processing point by a focused light diameter correction process described later, prior to executing processing and inspection of the workpiece WK.

[0025] FIG. 4 is a first graph showing the relationship between the focus shift amount and the focused light diameter. FIG. 5 is a second graph showing the relationship between the focus shift amount and the focused light diameter. FIG. 6 is a third graph showing the relationship between the focus shift amount and the focused light diameter. In FIG. 4 to FIG. 6, the horizontal axis represents the focus shift amount, and the vertical axis represents the focused light diameter. In FIG. 4 to FIG. 6, a plurality of measurement data obtained by irradiating the laser light LS from the laser head 200 with different degrees of contamination of the protective glass 280 and measuring the focus shift amount and the focused light diameter on the surface of the workpiece WK are represented by circles.

[0026] FIG. 4 shows measurement data when a command is given to the focal position changing unit 240 so that the defocus amount becomes 0 mm, FIG. 5 shows measurement data when a command is given to the focal position changing unit 240 so that the defocus amount becomes +30 mm, and FIG. 6 shows measurement data when a command is given to the focal position changing unit 240 so that the defocus amount becomes -30 mm. The focus shift amount was measured by the method described with reference to FIG. 2. The focus shift amount increases over time after the start of irradiation of the laser light LS and converges to a constant value. Therefore, it is preferable to measure the focus shift amount after a predetermined time has elapsed since the start of irradiation of the laser light LS. The focused spot diameter was measured using a focused spot analyzer.

[0027] 4 to 6 show an approximation line LN of the measurement data. The approximation line can be calculated, for example, by the least squares method. If the command value of the defocus amount is different, the slope of the approximation line LN is different. Regardless of the command value of the defocus amount, the greater the degree of contamination of the protective glass 280, the greater the focus shift amount, and the greater the focus shift amount, the larger the light collection diameter. When the command value of the defocus amount is positive, the greater the command value of the defocus amount, the smaller the slope of the approximation line.

[0028] 7 is an explanatory diagram showing a table TB representing the gradient of the approximation line LN for each command value of the defocus amount. In this embodiment, the memory 502 of the control device 500 stores a table TB representing the relationship between the command value of the defocus amount and the gradient of the approximation line LN, which is obtained by the method described using FIGS. 4 to 6.

[0029] 8 is a flowchart showing the content of the focused beam diameter correction process in this embodiment. The focused beam diameter correction process is executed by the control device 500 prior to processing and inspection of the workpiece WK by the laser processing machine 10. First, in step S110, the deviation amount acquisition unit 530 of the control device 500 acquires the current focus shift amount of the laser light LS. In this embodiment, the deviation amount acquisition unit 530 acquires the focus shift amount by the method described with reference to FIG.

[0030] Next, in step S120, the beam-focused diameter estimating unit 540 estimates the current beam-focused diameter of the laser beam LS at the processing point using the focus shift amount acquired by the deviation amount acquiring unit 530 and data representing the relationship between the focus shift amount when the contaminant M adheres to the protective glass 280 and the beam-focused diameter at the processing point. The data representing the relationship between the focus shift amount when the contaminant M adheres to the protective glass 280 and the beam-focused diameter at the processing point is stored in advance in the memory 502. In this embodiment, the table TB shown in FIG. 7 is stored in advance in the memory 502 as data representing the relationship between the focus shift amount when the contaminant M adheres to the protective glass 280 and the beam-focused diameter at the processing point. The beam-focused diameter estimating unit 540 reads the slope of the approximation line LN according to the current defocus amount command value from the table TB, and estimates the current beam-focused diameter using the increase in the beam-focused diameter from the target diameter obtained by multiplying the focus shift amount acquired by the deviation amount acquiring unit 530 by the slope of the approximation line LN.

[0031] In step S130, the correction execution unit 550 corrects the current focused diameter of the laser light LS at the processing point so that the current focused diameter of the laser light LS at the processing point is the same as the target diameter. In this embodiment, the correction execution unit 550 corrects the current focused diameter of the laser light LS at the processing point by moving the focus position F of the laser light LS using the focus position change unit 240. The correction execution unit 550 moves the focus position F by the total amount of a first movement amount L1 for moving the focus position F so that the focus shift amount becomes zero, and a second movement amount L2 for further moving the focus position F from the position where the focus shift amount becomes zero so that the focused diameter at the processing point becomes the target diameter. Thereafter, the correction execution unit 550 ends the focused diameter correction process. Note that the method executed by the focused diameter correction process may be called the focused diameter correction method of the laser processing machine 10. Step S110 of the light-collection diameter correction process may be referred to as a deviation amount acquisition step, step S120 as a light-collection diameter estimation step, and step S130 as a correction execution step.

[0032] Fig. 9 is an explanatory diagram showing a schematic diagram of the manner in which the focused diameter of the laser beam LS is corrected by the focused diameter correction process. At the time point (A) in Fig. 9, no contaminant M is attached to the protective glass 280 of the laser head 200. At the time point (A), the focal position F of the laser beam LS is located at the target position, and the focused diameter D1 of the laser beam LS at the processing point is the same as the target diameter.

[0033] As shown in (B) of Figure 9, when contaminant M adheres to the protective glass 280, the thermal lens effect of the protective glass 280 causes the focal position F of the laser light LS to move from the target position toward the laser head 200, and the scattering of the laser light LS by the contaminant M causes the focused diameter at the processing point to become larger than the target diameter.

[0034] 9C, even if the focal position F is moved toward the workpiece WK by the first movement amount L1, which is the same as the focus shift amount Lfs, so that the focal position F returns to the position at the time of (A), the focused diameter D2 at the processing point is larger than the focused diameter D1 at the processing point at the time of (A). In other words, in the state of (C), although the deviation of the focal position F from the target position due to the thermal lens effect is eliminated, the deviation of the focused diameter from the target diameter due to the scattering of the laser light LS is not eliminated.

[0035] 9(D), when the focal position F is further moved toward the workpiece WK by the second movement amount L2 from the position in the state of (C), the focused diameter D3 at the processing point becomes the same as the focused diameter D1 at the processing point at the time of (A), and the deviation of the focused diameter from the target diameter due to scattering of the laser light LS is eliminated. In this embodiment, the focused diameter correction process is executed, and the focal position F of the laser light LS and the focused diameter at the processing point are changed from the state of (B) to the state of (D).

[0036] According to the laser processing machine 10 in the present embodiment described above, the control device 500 executes the focused beam diameter correction process, thereby correcting the deviation of the focused beam diameter caused by the adhesion of the contaminant M to the protective glass 280. Therefore, it is possible to suppress a decrease in the quality of processing using the laser beam LS and the accuracy of inspection using the return beam caused by the deviation of the focused beam diameter at the processing point from the target diameter.

[0037] Furthermore, in this embodiment, the table TB stored in the memory 502 indicates that the greater the focus shift amount in the direction from the workpiece WK toward the laser head 200, the greater the focused beam diameter at the processing point. Therefore, by utilizing the phenomenon that the greater the degree of contamination of the protective glass 280, the greater the focus shift amount in the direction from the workpiece WK toward the laser head 200 due to the thermal lens effect, and the greater the degree of contamination of the protective glass 280, the greater the focused beam diameter at the processing point due to the scattering phenomenon of the laser light LS, the greater the focused beam diameter at the processing point can be appropriately corrected.

[0038] In this embodiment, the correction execution unit 550 moves the focal position F by the sum of a first movement amount L1 for moving the focal position F so that the focus shift amount becomes zero, and a second movement amount L2 for further moving the focal position F from the position where the focus shift amount becomes zero so that the focused diameter at the processing point becomes the target diameter. Therefore, the focused diameter can be corrected by moving the focal position F once, without moving the focal position F twice. Therefore, the correction of the focused diameter can be shortened.

[0039] Moreover, in this embodiment, the deviation amount acquiring section 530 acquires the focus shift amount using the return light detecting device 290. Therefore, the acquisition of the focus shift amount can be automated.

[0040] B. Other embodiments: (B1) In the first embodiment described above, the correction execution unit 550 corrects the focused diameter of the laser light LS at the processing point by changing the position of the Z lens 241 by the Z lens driving unit 242 of the laser head 200 in the focused diameter correction process to change the distance between the focal position F of the laser light LS and the workpiece WK. In contrast, the correction execution unit 550 may correct the focused diameter of the laser light LS at the processing point by changing the position of the laser head 200 by the head support unit 300 in the focused diameter correction process to change the distance between the focal position F of the laser light LS and the workpiece WK. In this case, the head support unit 300 is called a focal position change unit. Alternatively, a lifting device driven under the control of the control device 500 may be provided on the stage 400, and the lifting device may change the distance between the focal position F and the workpiece WK to correct the focused diameter of the laser light LS at the processing point. In this case, the lifting device provided on the stage 400 is called a focal position change unit.

[0041] (B2) In the first embodiment described above, the laser processing machine 10 is provided with a return light detection device 290 including a light receiving element 292. In contrast, the laser processing machine 10 does not necessarily need to be provided with a return light detection device 290. In this case, the deviation amount acquisition unit 530 may acquire, for example, a focus shift amount input by a user.

[0042] The present disclosure is not limited to the above-mentioned embodiment, and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features in the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention column can be appropriately replaced or combined to solve some or all of the above-mentioned problems or to achieve some or all of the above-mentioned effects. Furthermore, if the technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0043] 10...laser processing machine, 100...laser oscillator, 150...optical fiber, 200...laser head, 210...collimating lens, 220...dichroic mirror, 230...first reflecting mirror, 240...focus position changing section, 241...Z lens, 242...Z lens driving unit, 250...second reflecting mirror, 260...condensing lens, 270...irradiation position changing section, 271...X mirror, 272...X mirror driving unit , 276... Y mirror, 277... Y mirror drive unit, 280... protective glass, 290... light detection device, 291... third reflecting mirror, 292... light receiving element, 300... head support section, 400... stage, 500... control device, 510... processing execution section, 520... inspection execution section, 530... deviation amount acquisition section, 540... focused diameter estimation section, 550... correction execution section, F... focal position, LS... laser light, M... contaminant, WK... work

Claims

1. A laser processing machine, a focal position changing unit that changes a focal position of a laser beam emitted from a laser oscillator and transmitted through the lens with respect to a surface of the workpiece by changing a relative position between the lens and the workpiece; A protective glass disposed on a path of the laser light between the lens and the workpiece; a storage unit that stores in advance a relationship between an amount of deviation of the focal position of the laser light from a target position when a contaminant adheres to the protective glass and a focused diameter of the laser light on the surface of the workpiece; a deviation amount acquiring unit that acquires a current deviation amount of the focal position of the laser light from the target position; a beam diameter estimation unit that estimates a current beam diameter of the laser beam on the surface of the workpiece by using the current deviation amount acquired by the deviation amount acquisition unit and the relationship stored in the storage unit; a correction execution unit that corrects the current light-collection diameter by controlling the focal position change unit using the current shift amount acquired by the shift amount acquisition unit and the current light-collection diameter estimated by the light-collection diameter estimation unit; A laser processing machine comprising:

2. 2. The laser processing machine according to claim 1, The relationship indicates that the greater the deviation in the direction from the workpiece toward the lens, the greater the focused light diameter.

3. 2. The laser processing machine according to claim 1, The correction execution unit corrects the current focused diameter by moving the focal position by a total amount of a first movement amount that moves the focal position so that the current deviation amount is zero, and a second movement amount that further moves the focal position from the position where the current deviation amount is zero so that the focused diameter on the surface of the workpiece becomes a target diameter.

4. 2. The laser processing machine according to claim 1, A light receiving element is provided for receiving the laser light reflected by the workpiece, The deviation amount acquisition unit acquires the current deviation amount using the intensity of the laser light measured by the light receiving element.

5. A method for correcting a focal diameter of a laser processing machine equipped with a protective glass for protecting a lens, comprising: a deviation amount acquiring step of acquiring a current deviation amount from a target position of a focal position of the laser light which is transmitted through the lens and the protective glass and irradiated onto the surface of the workpiece; a beam diameter estimating step of estimating a current beam diameter of the laser beam on the surface of the workpiece, using the current deviation amount acquired in the deviation amount acquiring step, a previously acquired relationship between a deviation amount of the focal position of the laser beam from the target position when contaminants adhere to the protective glass, and a beam diameter of the laser beam on the surface of the workpiece; a correction execution step of correcting the current focused diameter by changing a relative position between the lens and the workpiece using the current deviation amount acquired in the deviation amount acquisition step and the current focused diameter estimated in the focused diameter estimation step; The method for correcting the focused beam diameter of a laser processing machine includes the steps of:

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