Laser processing monitoring device, laser processing system, and laser processing monitoring method

Abstract

In the present invention, a light reception unit measures the intensity of visible light in each of at least two determination wavelength bands from among visible light that is emitted from a site being processed by laser processing. A determination unit determines whether a laser processing condition is good or poor on the basis of the intensity of the light received by the light reception unit and in the at least two determination wavelength bands.

Description

Laser processing monitoring device, laser processing system, and laser processing monitoring method

[0001] The present invention relates to a laser processing monitoring device, a laser processing system, and a laser processing monitoring method.

[0002] A technique for determining the quality of laser welding based on the intensity of light reflected from the welding point and plasma light generated at the welding point is known (Patent Document 1). In the method described in Patent Document 1, plasma light is measured with a sensor, and the appropriateness of welding conditions is determined based on fluctuations in the absolute value of the measured plasma light. The sensor for detecting plasma light detects light with a wavelength of 300 nm to 900 nm.

[0003] JP 2010-240734 A

[0004] In the conventional methods, the accuracy of determining whether the laser processing conditions are appropriate may not be sufficient. An object of the present invention is to provide a laser processing monitoring device, a laser processing system, and a laser processing monitoring method that can improve the accuracy of determining whether the laser processing conditions are appropriate.

[0005] According to one aspect of the present invention, there is provided a laser processing monitoring device including: a light receiving unit that measures the intensity of each of at least two determination wavelength bands of visible light emitted from a processing location by laser processing; and a determination unit that determines whether or not laser processing conditions are appropriate based on the intensity of light of the at least two determination wavelength bands received by the light receiving unit.

[0006] According to another aspect of the present invention, there is provided a laser processing system comprising: a laser processing machine; and the above-mentioned laser processing monitoring device, wherein a portion of plasma light generated at a processing location of the laser processing machine is incident on the light receiving section of the laser processing monitoring device.

[0007] According to yet another aspect of the present invention, there is provided a laser processing monitoring method for measuring the intensities of light in at least two determination wavelength bands among plasma light generated at a processing location when laser processing is being performed on a processing object, and determining whether the laser processing conditions are appropriate based on the measurement results.

[0008] According to yet another aspect of the present invention, there is provided a laser processing monitoring device comprising: a light receiving unit that measures the intensity of light in a determination wavelength band among light emitted from a processing location by laser processing; and a judgment unit that judges the suitability of laser processing conditions based on the intensity of light received by the light receiving unit, wherein, when judging the suitability of the laser processing conditions, the judgment unit averages the intensity of light in the determination wavelength band for each of a plurality of different time widths, and judges the suitability of the laser processing conditions based on the average value of the intensity of light in the determination wavelength band.

[0009] By measuring the intensities of visible light in at least two determination wavelength bands, it is possible to improve the accuracy of determining whether the laser processing conditions are appropriate.

[0010] FIG. 1 is a schematic diagram of a laser processing monitoring device and a laser processing machine according to a first embodiment. FIG. 2 is a flowchart showing a processing procedure executed by the laser processing monitoring device. FIG. 3 is a flowchart showing an example of a detailed procedure for step SA1 in FIG. 2. FIG. 4 is a graph showing measurement results of the spectrum of plasma light generated at the processing location when laser welding was performed under various processing conditions in which the flow rate of the shielding gas was changed. FIG. 5 is a graph showing measurement results of the spectrum of plasma light generated at the processing location when laser welding was performed under various processing conditions in which the positional relationship between the surface of the workpiece and the focal position of the laser beam was changed. FIG. 6 is a graph showing measurement results of the spectrum of plasma light generated at the processing location when laser welding was performed under various processing conditions in which the laser output was changed. FIG. 7A is a graph showing the time change in the light intensity of plasma light, and FIG. 7B is a graph showing the moving average of the time change in FIG. 7A. FIG. 8 is a flowchart showing a processing procedure executed by the laser processing monitoring device according to a second embodiment. FIG. 9 is a flowchart showing a processing procedure for setting a judgment wavelength band in the laser processing monitoring device according to a third embodiment. FIG. 10 is a graph showing an example of spectrum data displayed on a display device. Fig. 11 is a chart showing an example of an image displayed on the display device when the user inputs information specifying the determination wavelength band. Fig. 12 is a schematic diagram of the laser processing monitoring device according to the fourth embodiment.

[0011] A laser processing monitoring device according to a first embodiment will be described with reference to Figures 1 to 7B. Figure 1 is a schematic diagram of a laser processing monitoring device 20 and a laser processing machine 50 according to the first embodiment. The laser processing monitoring device 20 and the laser processing machine 50 constitute a laser welding system.

[0012] First, the configuration of the laser processing machine 50 will be described. The laser processing machine 50 includes a dichroic mirror 51, a processing lens 52, and a collimating lens 53 housed in a housing 71. A laser beam transmitted through a laser transmission fiber 60 and output from the output end of the laser transmission fiber 60 enters the housing 71 from a side surface, is collimated by the collimating lens 53, is reflected by the dichroic mirror 51, passes through the processing lens 52, and is output from an opening at the tip of the housing 71. The laser beam output from the opening of the housing 71 is incident on a workpiece 90, thereby performing laser processing such as laser welding and laser cutting. As an example, a fiber laser oscillator that outputs a laser beam with a wavelength of approximately 1070 nm is used as a light source for the processing laser beam.

[0013] The dichroic mirror 51 has a reflectance of 95% or more in the wavelength range of the laser beam, and reflects most of the laser beam toward the work-piece 90. Light in other wavelength ranges is transmitted through the dichroic mirror 51.

[0014] Shielding gas is supplied from the gas tube 61 into the housing 71. The shielding gas supplied into the housing 71 is ejected toward the workpiece 90 from an opening at the tip of the housing 71. As the shielding gas, for example, an inert gas such as argon or helium is used.

[0015] A housing 72 of the laser processing monitoring device 20 is connected to the end of the housing 71 opposite the opening. The housing 72 accommodates two lenses 41, a half mirror 42, a laser light attenuation filter 43, and a camera condenser lens 44.

[0016] Plasma light is generated during the processing process by the incidence of the laser beam on the workpiece 90. Part of this plasma light and part of the scattered light from the surface of the workpiece 90 pass through the processing lens 52 and the dichroic mirror 51 and enter the housing 72 of the laser processing monitoring device 20. The two lenses 41 form a Galilean or Keplerian beam expander, which reduces the beam diameter of the light beam, such as the reflected light collimated by the processing lens 52 and the plasma light.

[0017] The visible light that has passed through the half mirror 42 passes through a laser light attenuation filter 43 and a camera condenser lens 44 and enters an imaging device 45. The laser light attenuation filter 43 attenuates light in the wavelength range of the processing laser beam. The imaging device 45 captures an image of the surface of the workpiece 90 and obtains a two-dimensional image of the surface of the workpiece 90. The laser light attenuation filter 43 can be replaced with an optical filter having optimal filter characteristics depending on the wavelength of the processing laser beam.

[0018] A lens barrel 21 is connected to the side of the housing 72. A portion of the plasma light generated at the processing location is reflected by the half mirror 42 and enters the lens barrel 21. A laser light attenuation filter 22, a neutral density filter 23, and a fiber condenser lens 24 are housed within the lens barrel 21. The lens barrel 21 has a filter holding structure that holds the laser light attenuation filter 22 in an exchangeable manner. The laser light attenuation filter 22 attenuates light in the wavelength range of the processing laser beam. The neutral density filter 23 attenuates light in all wavelength ranges almost evenly.

[0019] An optical fiber 25 is connected to the tip of the lens barrel 21. A fiber focusing lens 24 focuses the plasma light that has passed through the laser light attenuation filter 22 and the neutral density filter 23 onto the incident end face of the optical fiber 25. The plasma light that has entered the optical fiber 25 is output from the output end and enters the light receiving unit 30.

[0020] The laser light attenuation filter 22 and neutral density filter 23 are intended to keep the intensity of the light reflected by the half mirror 42 within the dynamic range of the light receiving unit 30. Because the light of the laser beam reflected from the workpiece is significantly stronger than light in other wavelength ranges, the neutral density filter 23 alone cannot keep it within the dynamic range of the light receiving unit 30. By inserting the laser light attenuation filter 22, it becomes possible to keep the light intensity in the wavelength range of the laser beam within the dynamic range of the light receiving unit 30.

[0021] The light receiving unit 30 measures the intensity of each of at least two determination wavelength bands of the incident visible light. The determination wavelength bands may be separated from each other, may be continuous, or may partially overlap each other. For example, a spectrometer is used as the light receiving unit 30. The measurement results by the light receiving unit 30 are input to the determination unit 31. The determination unit 31 includes a display device 32 that displays images, etc., and an input device 33 that inputs commands, etc., from the user.

[0022] The display device 32 may be, for example, a liquid crystal display, an organic EL display, etc. The input device 33 may be, for example, a keyboard, a pointing device, etc.

[0023] Next, the process for determining whether the laser processing conditions are appropriate, which is executed by the laser processing monitoring device 20, will be described with reference to Figures 2 and 3. Figure 2 is a flowchart showing the process procedure executed by the laser processing monitoring device 20. When laser welding is started, plasma light from the welding area is incident on the light receiving unit 30. The light receiving unit 30 measures the light intensity of the plasma light from the welding area in at least two determination wavelength bands, and the determination unit 31 acquires the measured values ​​(step SA1). Information specifying the determination wavelength bands is, for example, input in advance from the input device 33 and stored in the determination unit 31.

[0024] 3 is a flowchart showing an example of the detailed procedure of step SA1 (FIG. 2). The determination unit 31 collects time-series data of light intensity in a determination wavelength band (step SA11). Next, the determination unit 31 calculates a moving average value of the time-series data of light intensity (step SA12). The fixed time interval for calculating the moving average value is input, for example, from the input device 33 (FIG. 1) and stored in the determination unit 31.

[0025] 2, the determination unit 31 determines whether the laser processing conditions are appropriate based on the measured light intensity in the determination wavelength band, for example, the moving average value calculated in step SA12 (FIG. 3) (step SA2), and then outputs the determination result to the display device 32 (step SA3).

[0026] Next, with reference to FIGS. 4 to 6, the advantageous effect of determining whether the laser processing conditions are appropriate based on the light intensities in at least two determination wavelength bands will be described.

[0027] Figures 4 to 6 are graphs showing the measurement results of the spectrum of plasma light generated at the processing point when laser welding was performed under various processing conditions. The horizontal axis represents wavelength in units of nm, and the vertical axis represents light intensity in arbitrary units. Note that the light intensity shown in Figures 4 to 6 is the average value for one second during the processing period. Stainless steel was used as the object to be welded.

[0028] The graph shown in Figure 4 shows the spectrum of plasma light when the flow rate of the shielding gas, one of the processing conditions, is changed. The solid line a, dashed line b, solid line c, and dashed line d in Figure 4 show the light intensity when the flow rate of the shielding gas is 0 L / min, 6 L / min, 12 L / min, and 18 L / min, respectively. The target value of the shielding gas flow rate is 12 L / min. It can be seen that the spectral waveform changes when the flow rate of the shielding gas is changed from the target value. The amount of change in light intensity varies depending on the wavelength.

[0029] It can be seen that when the shielding gas flow rate fluctuates between 6 L / min and 18 L / min, the amount of change in light intensity is greater in the wavelength range of 700 nm to 750 nm. However, when the shielding gas flow rate decreases to 0 L / min, the amount of change in light intensity is greater in the wavelength range of 550 nm to 650 nm than in the wavelength range of 700 nm to 750 nm. That is, to detect fluctuations in the flow rate within a certain range from the target value of 12 L / min, it is preferable to measure the change in light intensity in the wavelength range of 700 nm to 750 nm. Furthermore, to detect when the shielding gas is shut off and the flow rate has reached nearly zero, it is preferable to measure the change in light intensity in the wavelength range of 550 nm to 650 nm than in the wavelength range of 700 nm to 750 nm.

[0030] By determining the suitability of laser processing conditions based on the light intensity in two determination wavelength bands, a wavelength range of 550 nm to 650 nm and a wavelength range of 700 nm to 750 nm, it is possible to improve the accuracy of determining the suitability of the shielding gas flow rate between 6 L / min and 18 L / min, and the state when the shielding gas is shut off (flow rate is zero).

[0031] As shown in FIG. 4, regardless of the flow rate of the shielding gas, two peaks appear in the spectral waveform in the wavelength range of visible light (wavelength range of approximately 400 nm or more and 800 nm or less).

[0032] The graph shown in Figure 5 shows the spectrum of plasma light when the surface of the workpiece is displaced from the focal position (position of the beam waist). The solid line a, dashed line b, solid line c, dashed line d, and solid line e in Figure 5 show the light intensity when the amount of displacement from the focal position is -1.5 mm, -0.75 mm, 0 mm, +0.75 mm, and +1.5 mm, respectively. A negative amount of displacement means that the surface of the workpiece is displaced from the focal position in a direction approaching the light source, and a positive amount of displacement means that the surface of the workpiece is displaced in the opposite direction. Regardless of the value of the amount of displacement from the focal position, two peaks appear in the spectral waveform in the visible light wavelength range.

[0033] It can be seen that when the surface of the workpiece is deviated from the focal position, the amount of change in light intensity in the wavelength range of 500 nm to 550 nm is large. When the surface of the workpiece is deviated toward the light source, the light intensity increases, and when the surface of the workpiece is deviated away from the light source, the light intensity decreases. Therefore, by comparing the light intensity when just in focus with the measured value of the light intensity in the wavelength range of 500 nm to 550 nm, it is possible to determine whether or not the surface is deviated from the focal position, and the direction of the deviation.

[0034] When the amount of deviation from the focal position is zero, the light intensity in the wavelength range of 500 nm to 550 nm is approximately equal to the light intensity in the wavelength range of 700 nm to 750 nm. In other words, the ratio between the two is approximately 1. As the amount of deviation from the focal position increases, the absolute value of the difference between the light intensity in the wavelength range of 500 nm to 550 nm and the light intensity in the wavelength range of 700 nm to 750 nm increases, and the ratio between the two deviates from 1. Therefore, it is possible to determine whether or not there is a deviation from the focal position and the amount of deviation based on the difference or ratio between the light intensity in the wavelength range of 500 nm to 550 nm and the light intensity in the wavelength range of 700 nm to 750 nm.

[0035] The graph in Figure 6 shows the spectrum of plasma light when the laser output, one of the processing conditions, is changed. The solid line a, dashed line b, solid line c, dashed line d, and solid line e in Figure 6 show the light intensity when the laser output is set to 300 W, 450 W, 600 W, 750 W, and 900 W, respectively. Regardless of the laser output value, two peaks appear in the spectral waveform in the visible light wavelength range.

[0036] When the laser output changes, the light intensity in the wavelength range of 500 nm to 550 nm and the light intensity in the wavelength range of 700 nm to 750 nm change to approximately the same extent. That is, the amount of change in the absolute value of the difference between the two light intensities and the amount of change in the ratio are smaller than in the case of deviation from the focal position shown in Figure 5. Therefore, based on the amount of change in the difference or ratio between the light intensity in the wavelength range of 500 nm to 550 nm and the light intensity in the wavelength range of 700 nm to 750 nm, it is possible to distinguish whether deviation from the focal position has occurred or whether the laser output is fluctuating.

[0037] Fluctuations in laser power have a significant effect on the penetration depth of the weld. Also, deviations from the focal point on the surface of the workpiece do not have as great an effect on the penetration depth as fluctuations in laser power. Distinguishing between deviations from the focal point and fluctuations in laser power is effective in predicting the penetration depth.

[0038] Next, with reference to FIGS. 7A and 7B, the excellent effect of using the moving average value of the light intensity when determining whether the laser processing conditions are appropriate will be described.

[0039] Fig. 7A is a graph showing the change in light intensity of plasma light over time, and Fig. 7B is a graph showing the moving average of the change over time in Fig. 7A. Fig. 7A shows measured values ​​of light intensity obtained at a sampling frequency of 58 Hz, and Fig. 7B shows the moving average value over one second. The horizontal axis represents time in units of seconds, and the vertical axis represents light intensity in arbitrary units. The solid and dashed lines in Fig. 7A and Fig. 7B respectively show the light intensity when the laser output is the target value of 600 W and when the laser output drops to 750 W due to some kind of malfunction.

[0040] 7A, the time variation of the light intensity acquired at a sampling frequency of 58 Hz has overlapping portions when the laser output is 600 W and 750 W. This makes it difficult to accurately detect fluctuations in the laser output from the time-series data of the light intensity acquired at a sampling frequency of 58 Hz.

[0041] As shown in Figure 7B, the one-second moving average value of the measured light intensity values ​​clearly separates the cases where the laser output is 600 W and 750 W. For example, if the judgment threshold is set to 2495 in arbitrary units on the vertical axis of Figure 7B, it is possible to accurately distinguish between the cases where the laser output is 600 W and 750 W. In this way, by using the moving average value of the collected measured light intensity values, it is possible to improve the accuracy of determining whether the laser processing conditions are appropriate. The time width for taking the moving average is not limited to one second, and other time widths may be used.

[0042] Next, another advantageous effect of the first embodiment will be described. In the first embodiment, a spectroscope is used in the light receiving unit 30. This makes it possible to collect measured values ​​of light intensity over a wide wavelength range. From the collected measured values, measured values ​​within wavelength ranges included in at least two desired determination wavelength bands are selected and averaged, and the appropriateness of the laser processing conditions can be determined based on the average measured values. Therefore, even if the determination wavelength band changes, it is possible to accommodate this change simply by modifying the software (program or data) that executes the processing of step SA1 ( FIG. 2 ) of the determination unit 31, without changing the hardware of the light receiving unit 30.

[0043] Even when the wavelength of the laser beam used in laser processing is changed, this can be easily accommodated by replacing the laser light attenuation filters 22 and 43 (FIG. 1) with optical filters having filter characteristics according to the wavelength of the laser beam.

[0044] If a spectroscope that covers the wavelength of the processing laser beam, visible light, and infrared light is used as the light receiving unit 30, it is possible to measure the intensity of the reflected light of the laser beam from the workpiece, the intensity of the plasma light generated at the processing location, and the intensity of the thermal radiation light from the processing location. By measuring the intensity of the reflected light of the laser beam and the thermal radiation light in addition to the light intensity of the plasma light in the judgment wavelength band, the accuracy of determining whether the laser processing conditions are appropriate can be improved.

[0045] Next, a modified example of the first embodiment will be described. In the first embodiment, the suitability of the laser processing conditions is determined based on the measured values ​​of the light intensities in at least two determination wavelength bands, the ratio of the light intensities in the two determination wavelength bands, etc. However, it is also possible to perform machine learning to learn the relationship between the light intensity trend and the laser processing conditions, and determine the suitability of the laser processing conditions using the learning results. For example, the determination unit 31 can perform machine learning based on data indicating the light intensities in at least two determination wavelength bands and the determination results of the suitability of the laser processing conditions when the data was measured, and determine the suitability of the laser processing conditions using the machine learning results.

[0046] In the first embodiment, a spectroscope is used for the light receiving unit 30 (FIG. 1), but other optical systems capable of measuring the light intensity in each of multiple wavelength ranges may also be used. For example, multiple dichroic mirrors with different wavelength characteristics may be used to split the plasma light into wavelengths, and the light intensity of each of the split plasma light may be measured.

[0047] Next, a laser processing monitoring device according to a second embodiment will be described with reference to Fig. 8. Hereinafter, a description of components common to the laser processing monitoring device according to the first embodiment described with reference to Figs. 1 to 7B will be omitted. In the first embodiment, the time interval for calculating the moving average value described with reference to Figs. 7A and 7B is fixed to one, but in the second embodiment, the moving average value is calculated over a plurality of time intervals.

[0048] 8 is a flowchart showing the processing procedure executed by laser processing monitoring device 20 ( FIG. 1 ) according to the second embodiment. First, laser welding is started under set laser processing conditions (step SB1). During laser welding, determination unit 31 ( FIG. 1 ) collects measured values ​​of the light intensity of the plasma light at a predetermined sampling frequency and stores them in memory (step SB2). When laser welding of a predetermined range is completed, laser welding ends (step SB3).

[0049] The time width for calculating the moving average is set to an initial value (step SB4). Then, the moving average is calculated for the set time width over the data collection period from the data stored in memory (step SB5). It is determined whether calculation has been completed for all of the multiple set values ​​of the time width for which the moving average is to be calculated (step SB6). If there are any set values ​​of the time width that have not yet been calculated, the set value of the time width for calculating the moving average is corrected (step SB7), and steps SB5 and SB6 are repeated. The multiple set values ​​of the time width for the moving average are input in advance from the input device 33 and stored in the determination unit 31.

[0050] When the calculation of the moving average values ​​for all the set values ​​of the time width to be calculated has been completed, the appropriateness of the laser processing conditions is determined for each of the set values ​​of the time width for which the moving average values ​​are calculated (step B8), and the determination results are then output (step SB9).

[0051] Next, the excellent effects of the second embodiment will be described. In the second embodiment, by using a moving average value calculated by setting the time interval for taking the moving average to a short value, it becomes possible to detect the occurrence of short-term defects in laser processing conditions. Furthermore, by using a moving average value calculated by setting the time interval for taking the moving average to a long value, it becomes possible to accurately detect the occurrence of long-term defects in laser processing conditions. This excellent effect is not limited to the case where the intensity of light in at least two determination wavelength ranges is measured or the case where the intensity of light in the wavelength range of visible light is measured. For example, this excellent effect can also be obtained when the intensity of light in one determination wavelength range is measured. Furthermore, this excellent effect can also be obtained when the intensity of light in the infrared or ultraviolet range is measured.

[0052] Next, a laser processing monitoring device according to a third embodiment will be described with reference to Figures 9 to 11. Hereinafter, a description of components common to the laser processing monitoring device according to the first embodiment described with reference to Figures 1 to 7B will be omitted. In the first embodiment, the wavelength range of the determination wavelength band for obtaining the measured light intensity value in step SA1 (Figure 2) is set in advance and cannot be changed by the user. In contrast, in the third embodiment, the wavelength range of the determination wavelength band can be changed by the user.

[0053] 9 is a flowchart showing the processing procedure for setting the wavelength range of the determination wavelength band by the laser processing monitoring device according to the third embodiment. First, laser welding is performed under the set laser processing conditions, and spectral data of plasma light from the welded area is collected and saved (step SC1). If further data collection is required, the laser processing conditions are changed (steps SC2 and SC3), and the collection and saving of spectral data is repeated (step SC1).

[0054] When the data collection is completed, graphs of the spectrum data of the laser welding performed under a plurality of laser processing conditions are superimposed and displayed on the display device 32 (FIG. 1) (step SC4).

[0055] Figure 10 is a graph showing an example of spectral data displayed on the display device 32. The horizontal axis represents wavelength in units of nm, and the vertical axis represents light intensity in arbitrary units. The solid line a, dashed line b, and solid line c in Figure 10 represent measured light intensity values ​​when welding was performed under laser processing conditions A, B, and C, respectively. By looking at this graph, the user can determine the wavelength range that is most suitable for distinguishing between conditions A, B, and C.

[0056] As shown in FIG. 9, the determination unit 31 (FIG. 1) prompts the user to input information specifying the wavelength range of the determination wavelength band and acquires the input information (step SC5). For example, the user may look at the graph shown in FIG. 10 to determine the wavelength range that is most suitable for distinguishing between conditions A, B, and C, and select that wavelength range as the determination wavelength band. As described with reference to FIGS. 4 to 6, two peaks typically appear in the spectral waveform of the visible light wavelength range. The heights of these two peaks change depending on the processing conditions. Therefore, it is preferable to select two determination wavelength bands from the visible light wavelength range. In particular, it is preferable to select the wavelength range of the peaks that appear in the spectral waveform as the determination wavelength band.

[0057] 11 is a diagram showing an example of an image displayed on the display device 32 (FIG. 1) when the user inputs information specifying the wavelength range of the determination wavelength band. A list correlating the determination wavelength band number with the wavelength range is displayed. The user inputs the lower and upper limits of the wavelength range in the wavelength range column of this list. In the example shown in FIG. 11, for example, a wavelength range of 400 nm to 450 nm is associated with determination wavelength band number #1.

[0058] When the user inputs information specifying the wavelength range of the determination wavelength band, the determination unit 31 stores the input information specifying the wavelength range of the determination wavelength band (step SC6), as shown in Fig. 9. In step SA1 shown in Fig. 2, the determination unit 31 acquires the measured light intensity values ​​of the determination wavelength band specified by the information stored in step SC6 (Fig. 11). For example, if a spectrometer is used as the light receiving unit 30, the average value of the measured light intensity values ​​of the wavelengths included in the wavelength range of the determination wavelength band is used as the measured light intensity value of the determination wavelength band.

[0059] Next, the advantageous effects of the third embodiment will be described. In the third embodiment, the user can view the spectrum data shown in Fig. 10 and specify a wavelength range of a preferred determination wavelength band for determining whether the laser processing conditions are appropriate. Furthermore, when laser processing is performed under different processing conditions depending on the workpiece or processing mode, it is possible to specify a preferred wavelength range of a determination wavelength band for each different processing condition.

[0060] Next, a laser processing system according to a fourth embodiment will be described with reference to Fig. 12. Below, a description of the configuration common to the laser processing system according to the first embodiment described with reference to Figs. 1 to 7B will be omitted.

[0061] 12 is a schematic diagram of a laser processing system according to a fourth embodiment. In the first embodiment (FIG. 1), the path of the laser beam is fixed relative to the processing lens 52. In contrast, in the fourth embodiment, the path of the laser beam is vibrated or rotated relative to the processing lens 52 to perform wobble welding.

[0062] The laser beam output from the laser transmission fiber 60 is incident on the wobble mechanism 67. The laser beam wobbled by the wobble mechanism 67 is incident on the dichroic mirror 51. The wobble mechanism 67 includes a pair of galvanometer mirrors 65X and 65Y, and motors 66X and 66Y that oscillate the galvanometer mirrors 65X and 65Y.

[0063] The plasma light generated at the processing location where the wobble processing is being performed passes through the processing lens 52 and the dichroic mirror 51 and enters the laser processing monitoring device 20, as in the first embodiment.

[0064] Next, the advantageous effects of the fourth embodiment will be described. In the fourth embodiment, wobble welding is performed, thereby improving the welding quality. The laser processing monitoring device 20 according to the first embodiment can also be applied to a laser processing machine that performs wobble welding.

[0065] The above-described embodiments are merely examples, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. Similar effects resulting from similar configurations of multiple embodiments will not be mentioned sequentially for each embodiment. Furthermore, the present invention is not limited to the above-described embodiments. For example, it will be obvious to those skilled in the art that various modifications, improvements, combinations, etc. are possible.

[0066] 20 Laser processing monitoring device 21 Lens barrel 22 Laser light attenuation filter 23 Neutral density filter 24 Fiber condenser lens 25 Optical fiber 30 Light receiving unit 31 Determination unit 32 Display device 33 Input device 41 Lens 42 Half mirror 43 Laser light attenuation filter 44 Camera condenser lens 45 Imaging device 50 Laser processing machine 51 Dichroic mirror 52 Processing lens 53 Collimator lens 60 Laser transmission fiber 61 Gas tube 65X, 65Y Galvanometer mirror 66X, 66Y Motor 67 Wobble mechanism 71, 72 Housing 90 Processing object

Claims

1. A laser processing monitoring device comprising: a light receiving unit that measures the intensity of each of at least two determination wavelength bands of visible light emitted from a processed area by laser processing; and a judgment unit that judges whether the laser processing conditions are appropriate based on the intensity of the light of at least two of the determination wavelength bands received by the light receiving unit.

2. A laser processing monitoring device as set forth in claim 1, wherein the light receiving section includes a spectroscope.

3. A laser processing monitoring device as described in claim 1 or 2, further comprising a filter holding structure for holding a replaceable laser light attenuation filter that attenuates light in a specific wavelength range in the path of light incident on the light receiving unit.

4. A laser processing monitoring device as described in claim 1 or 2, wherein the judgment unit further includes: a display device that displays an image of the spectral data of the light measured by the light receiving unit; and an input device that allows a user to input information specifying the judgment wavelength band based on the displayed spectral data.

5. A laser processing monitoring device as described in claim 1 or 2, wherein the judgment unit, when judging the suitability of the laser processing conditions, averages the intensity of light in the judgment wavelength band for each of a number of different time widths, and judges the suitability of the laser processing conditions based on the average value of the intensity of light in the judgment wavelength band.

6. A laser processing monitoring device as described in claim 1 or 2, wherein the judgment unit performs machine learning based on data indicating the intensity of light in the judgment wavelength band and a judgment result of the suitability of the laser processing conditions at the time the data was measured, and judges the suitability of the laser processing conditions using the results of the machine learning.

7. A laser processing system comprising: a laser processing machine; and the laser processing monitoring device according to claim 1 or 2, wherein a portion of plasma light generated at a processing location of the laser processing machine is incident on the light receiving portion of the laser processing monitoring device.

8. A laser processing monitoring method which measures the light intensity of at least two judgment wavelength bands of plasma light generated at a processing point when laser processing is being performed on a processing object, and determines the suitability of the laser processing conditions based on the measurement results.

9. A laser processing monitoring device comprising: a light receiving unit that measures the intensity of light in a determination wavelength band among the light emitted from a processed part by laser processing; and a judgment unit that judges the suitability of laser processing conditions based on the intensity of the light received by the light receiving unit, wherein when judging the suitability of the laser processing conditions, the judgment unit averages the intensity of light in the determination wavelength band for each of a plurality of different time widths, and judges the suitability of the laser processing conditions based on the average value of the intensity of light in the judgment wavelength band.

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