JP3227650B2 - Laser welding machine and laser welding condition monitoring method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to defect detection in a laser welding machine, and more particularly to a laser welding state for detecting light from a welding point and detecting welding defects and evaluating a bead size based on the intensity of the light. Laser welding with monitoring function
And a laser welding state monitoring method.

[0002]

2. Description of the Related Art In laser welding, a target workpiece is irradiated with pulsed or continuous laser light output from a laser oscillator to perform welding. Inspection of welding defects in laser welding is often performed by an inspector off-line visually or by using inspection equipment. In this case, mass production lines such as automobile manufacturing require inspection of a large number of places, and the burden on inspectors is large. Further, the inspection time needs to be short from the viewpoint of the productivity of the production line, and it is most desirable to perform the defect inspection in parallel with the welding.

The following method has been proposed by the present inventor as an on-line measurement technique of the welding state in laser welding.

[0004] This technique will be described with reference to FIG. In FIG. 11, a pulsed laser beam generated by a YAG laser oscillator 11 is guided to a laser torch 12 by a transmission fiber, and a work 14 is passed through a YAG laser reflecting mirror 13 in the laser torch 12 and an optical lens (not shown).
Irradiation is performed for welding.

[0005] In the housing of the laser torch 12, a work 1 is provided.
Laser light applied to 4 (hereinafter referred to as irradiation laser light)
A condensing lens 15 for condensing light (hereinafter, referred to as welding light) emitted from the welding portion so as to be coaxial with the optical axis of the laser beam is provided. The welding light includes plasma light generated during the welding process, reflected light of irradiation laser light, and ambient light. In the YAG laser reflecting mirror 13, most of the reflected laser light emitted from the welded portion is reflected, but a very small portion is transmitted, and the plasma light is transmitted as it is.

After the condenser lens 15, there is provided a YAG light reflecting mirror 16 which reflects only the reflected light of the irradiation laser light out of the welding light and transmits the remaining light. A YAG light cut filter 17 for extracting only the plasma light generated during the welding process from the transmitted light of the YAG light reflecting mirror 16 is provided on the transmitting portion side of the YAG light reflecting mirror 16.
On the other hand, the YAG light reflecting mirror 16 has a reflecting portion on the YAG light reflecting mirror 16 side.
A YAG light transmission bandpass filter 18 for extracting only the reflected light of the irradiation laser light from the light reflected by the light reflecting mirror 16 is provided.

[0007] As described above, the laser torch 12
Inside, there is provided a YAG laser reflection mirror 13 for reflecting laser light from the YAG laser oscillator 11 and irradiating the work 14 with the laser light. For this reason, the reflected light of the irradiation laser light is reflected by the YAG laser reflecting mirror 13 and a part thereof is condensed by the condenser lens 15 as leak reflected light. In other words, only a part of the reflected light of the irradiation laser light included in the welding light reaches the condenser lens 15.

With the above-described configuration, the welding light emitted from the welding portion of the work 14 is condensed by the converging lens 15 installed coaxially with the irradiation laser light, and the YAG light reflecting mirror 16 condenses the welding light.
By reflecting only the AG light, it is separated into plasma light and reflected light. After the separation, the plasma light is cut through a YAG light cut filter 17 in a wavelength range other than the plasma light. The light that has exited the YAG light cut filter 17 is converted into a voltage signal according to the received light intensity by a photodiode 20 as a photoelectric conversion element and an amplifier 21 and output to a welding state determination processing device 23.

On the other hand, the reflected light from the YAG light reflecting mirror 16 is cut through a YAG light transmission bandpass filter 18 so that light in a wavelength range other than the YAG light is cut off. The light exiting the YAG light transmission bandpass filter 18 is converted into a voltage signal according to the received light intensity by a photodiode 24 as a photoelectric conversion element and an amplifier 25 and output to a welding state determination processing device 23.

[0010] The welding state determination processing device 23 includes an amplifier 2
Judgment processing such as defect detection is performed based on the voltage signals from 1 and 25, and the result is displayed and recorded on the display device 26 or the storage device 27 as necessary. A processing algorithm for defect detection is described in, for example, “Laser Welding Defect Detector (Japanese Patent Application No. 9-213) already filed by the present applicant.
No. 223) ".

In brief, a processing algorithm for detecting a defect is a low-pass filter for removing a predetermined high-frequency component from a digital voltage signal, and a differential signal is output by differentiating the output of the low-pass filter. And a first processing unit for determining whether the value of the digital voltage signal exceeds a first threshold value L1.
And a first processing means for detecting a second defect based on whether the value of the digital voltage signal is lower than a second threshold L2 lower than the first threshold L1. A third threshold value L3 and a fourth threshold value L3 between which the value of the differential signal is zero when the value of the differential signal is zero.
4 (where L3> L4), and a second processing means for detecting whether the value exceeds the range, and receiving the detection result of the second processing means and the detection result of the first processing means, 2
And a defect type discriminating processing unit that detects the output as a third defect when there is an output from only the processing means.

With this configuration, the defect detection can be performed by executing the processing algorithm for defect detection on the two voltage signals from the amplifiers 21 and 25.

[0013]

According to this method, the reflected light of the irradiation laser light and the plasma light that are two-dimensionally condensed by the condensing lens 15 are each applied to one photodiode 2.
0, 24, the photodiodes 20, 24
Is the total amount of light intensity received on the light receiving surface of the light receiving surface. On the other hand, the two-dimensional distribution of the reflected light of the irradiation laser light and the intensity of the plasma light may change depending on the welding state.

FIG. 12 is a schematic diagram (schematically drawn in one dimension) of a change in the distribution of the reflected laser light in the photodiode, and FIG. 12 (b) is an example of a case where welding is poor in melting. In FIG. 12, when the total amount of the reflected light intensity of the irradiation laser light is the same in both FIGS. 12A and 1B (that is, when the area of the hatched portion in the drawing is equal),
With the above-described method, a change in the molten state cannot be detected.

An object of the present invention is to provide a laser welding state monitoring function capable of improving the defect detection accuracy by arranging a plurality of photoelectric conversion elements.
To provide a contactor .

Another object of the present invention is to provide a laser welding state monitoring method suitable for the above laser welding machine .

[0017]

This onset bright [Means for solving problems], in the laser welding machine for performing welding by irradiating a workpiece with a laser beam in laser torch, in the housing of the laser torch, the light of the laser light radiated on the workpiece Reflected light of plasma light and laser light emitted from the welding point so as to be coaxial with the axis
The condensing the condenser lens provided that, two-dimensional light-receiving means for receiving a plasma light condensed by the condenser lens
And the reflected light of the laser light condensed by the condenser lens.
Arrange two-dimensional light receiving means for emitting light to receive light.
Defect detection of a welding location is performed based on the two-dimensional distribution of the intensity of the reflected light of the plasma light and the laser light .

In this laser welding machine , a first laser light reflecting mirror that reflects only the reflected light of the laser light and transmits the remaining light is provided after the condenser lens, and the first laser light reflecting mirror is provided. A first filter for extracting only plasma light generated during the welding process from the transmitted light of the laser light reflecting mirror; and a first filter for extracting only the reflected light of the laser light from the reflected light of the laser light reflecting mirror. A second filter is provided.

The two-dimensional light receiving means includes, after the first filter, an optical fiber and a plurality of photoelectric conversion elements for photoelectrically converting the light received by the optical fiber as a first group. After the second filter, it is preferable that an optical fiber and a plurality of photoelectric conversion elements that photoelectrically convert light received by the optical fiber be arranged as a second group.

In the laser torch, there is provided a second laser light reflecting mirror for reflecting laser light from a laser transmission fiber connected to a laser oscillation source and irradiating the laser light to the work. The optical lens is the second
The welding light emitted from the welding location is condensed through the laser light reflecting mirror.

[0021] In addition, the defect detection at the welding portion is performed based on the levels of the plurality of electric signals from the photoelectric conversion elements of the first group and the levels of the plurality of electric signals from the photoelectric conversion elements of the second group. A determination processing device for performing, for each of the first group and the second group, determining whether the level of a plurality of electrical signals is within a predetermined range, respectively. When within the predetermined range, "
0 ”,“ 1 ”when out of the predetermined range
Is output as a determination result, a predetermined weight is applied to each determination result, and the presence or absence of a defect is determined by comparing the sum of the weighted values with a predetermined threshold value.

[0022] The determination processing device may further perform welding based on a plurality of electric signal levels from the first group of photoelectric conversion elements and a plurality of electric signal levels from the second group of photoelectric conversion elements. An evaluation unit that evaluates the size of the bead, wherein the evaluation unit is configured such that, for each of the first group and the second group, the level of each of the plurality of electric signals is higher than a predetermined threshold. It may be determined whether or not the welding bead is to be used to evaluate the depth and width of the weld bead based on the number of electric signals higher than the preset threshold.

Further, as the two-dimensional light receiving means, a first CCD camera capable of detecting visible light and infrared light is disposed after the first filter, and a visible light and an infrared light can be detected after the second filter. Second CC that can detect light and infrared light
A D camera may be arranged.

In the case where a CCD camera is used, a judgment processing device is provided for individually performing image processing on the image from the first CCD camera and the image from the second CCD camera to detect a defect at a welding position. The determination processing device includes a luminance level (hereinafter referred to as a first luminance level) for each pixel from the first CCD camera.
Luminance level group) and a luminance level of each pixel from the second CCD camera (hereinafter, referred to as a second luminance level group). And outputs "0" as a determination result when the value is outside the predetermined range, and outputs "1" as a value outside the predetermined range. Weighting is performed, and the presence or absence of a defect is determined by comparing the sum of the weighted values with a predetermined threshold value. When a CCD camera is used, the determination processing device may further include a plurality of electric signal levels from the first group of photoelectric conversion elements and a plurality of electric signal from the second group of photoelectric conversion elements. Evaluation means for evaluating the size of the weld bead based on the level of the plurality of electric signals, wherein the evaluation means sets in advance the levels of the plurality of electric signals for each of the first group and the second group. It may be determined whether the threshold value is higher than the predetermined threshold value and the depth and width of the weld bead can be evaluated based on the number of electrical signals higher than the preset threshold value.

According to the present invention, when welding is performed by irradiating the workpiece with a laser beam, the inside of the housing of the laser torch can be used.
And coaxial with the optical axis of the laser beam applied to the work.
Become manner emanating from the welding location, the reflection light of the plasma light and laser light condensed, the condensed plasma light,
Laser light received and focused by two- dimensional light receiving means
Light reflected by the two-dimensional light receiving means
-Dimensional component of reflected plasma and laser light intensity
A laser welding state monitoring method is provided, wherein a defect of a welding location is detected based on a cloth .

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser welding machine according to a preferred embodiment of the present invention will be described with reference to FIG. The same parts as those in FIG. 11 are denoted by the same reference numerals. YA
The YAG laser light from the G laser oscillator 11 is guided to the laser torch 12 and the work 14 is passed through a YAG laser reflecting mirror 13 in the laser torch 12 and an optical lens (not shown).
Irradiation is performed for welding. A condensing lens 15 in which welding light emitted from a welding portion of the work 14 is coaxially arranged with the irradiation laser light.
Then, only the YAG light is reflected by the YAG light reflection mirror 16 to be separated into plasma light and reflected light of the irradiation laser light. After the separation, the plasma light passes through the YAG light cut filter 17, and the plurality of optical fibers 2 arranged densely are arranged.
Is received at. The received plasma light is photoelectrically converted by a photodiode 3 individually coupled to each optical fiber 2.

On the other hand, the reflected light of the irradiation laser light passes through the YAG light transmission bandpass filter 18 and is received by a plurality of optical fibers 4 arranged closely. The received plasma light is photoelectrically converted by a photodiode 5 individually coupled to each optical fiber 4. Photodiodes 3, 5
Each of the plurality of voltage signals photoelectrically converted in step (1) is amplified by an amplifier (not shown) and input to the welding state determination processing device 6. The welding state determination processing device 6 performs processing such as defect detection based on the levels of the plurality of input voltage signals,
The result is displayed and recorded on the display device 26 or the storage device 27 as needed. That is, the welding state determination processing device 6
Performs processing such as defect detection on the plurality of voltage signals from the photodiode 3 and the plurality of voltage signals from the photodiode 5 separately.

FIG. 2 shows the relationship between the optical fiber 2 and the photodiode 3. A plurality of optical fibers 2 are densely arranged, and the ends are aligned in a plane, and the welding light is focused thereon. In FIG. 2, nine optical fibers 2 are densely arranged, but the number and the diameter of one fiber are appropriately selected. The light transmitted by the optical fiber 2 is received by one photodiode 3 for each optical fiber. Such a relationship is the same for the optical fiber 4 and the photodiode 5.

The reason why the optical fibers 2 or 4 are used is that the optical fibers can be densely arranged so as not to form a gap as shown in FIG. On the other hand, it is difficult to arrange the photodiodes so far densely so as not to form a gap due to their shape.
However, if the photoelectric conversion elements, including the photodiodes, can be arranged densely without gaps, the photoelectric conversion elements directly receive the reflected light of plasma light or irradiation laser light without using optical fibers. You may do it.

On the other hand, instead of a combination of an optical fiber and a photodiode, a visible / infrared CCD camera 7 is used as shown in FIG.
May be used. Here, the visible / infrared CCD camera is a CCD camera capable of detecting visible light and infrared light. The reflected light of the irradiation laser light and the plasma light are received by separate visible / infrared CCD cameras 7, respectively, and the images are transmitted to the welding state determination processing device 6. However, since the visible / infrared CCD camera 7 transmits an image at a cycle of about 30 msec, a defect may be overlooked (an image cannot be acquired when a defect occurs) depending on the timing. In the configuration using the visible / infrared CCD camera 7, an image processing device is installed in the welding state determination processing device 6. This image processing apparatus detects the luminance of each pixel of the image from the visible / infrared CCD camera 7 and performs processing such as defect detection based on the detected luminance level. In this case, one pixel corresponds to one optical fiber in FIG. 1, but a plurality of adjacent pixels are defined as one determination area corresponding to one optical fiber, and the sum of the luminance levels of the plurality of pixels is determined. May be calculated, and defect detection may be performed based on this sum.

FIG. 4 is a block diagram showing the configuration of the welding state determination processing device 6 applied to the configuration of FIG. A plurality of voltage signals photoelectrically converted by the photodiode 3 (5) are
The digital signal is converted by the / D converter 6-1 and the CPU 6-
2. The high-speed signal processor 6-3 determines a welding state such as a defect detection according to a predetermined processing algorithm. For convenience, a plurality of voltage signals photoelectrically converted by the photodiode 3 and a plurality of voltage signals photoelectrically converted by the photodiode 5 are input to the A / D converter 6-1. Needless to say, this is done. The configuration itself of such a device is general as a signal processing device, and can be easily realized using a personal computer.

When the visible / infrared CCD camera 7 shown in FIG. 3 is used, the A / D converter 6-1 is replaced with an image processing device.

An algorithm for detecting a defect and evaluating a weld bead in the welding state determination processing device 6 will be described below.
For the sake of convenience, the description will be made in a batch manner. In practice, however, the arithmetic processing is sequentially performed using the level of the measurement signal.

(1) Defect Detection FIG. 5 shows a time series of waveforms of measurement signals when welding light (reflected light of plasma light or irradiation laser light) is received by n optical fibers. As shown in FIG. 5, when a welding defect occurs, the level of the measurement signal changes significantly. Therefore, a defect can be detected by setting an appropriate threshold value and detecting a level change. The procedure is shown below.

A high-frequency component is removed from the signal after the A / D conversion processing by a digital low-pass filter processing. As a result, a processed signal as shown in FIG. 6 is obtained.

A certain range is set by predetermined threshold values a and b. It is determined whether or not the level of the processed signal is within this range. If the level is within this range, "0" is set. If not, a flag is set as a defect candidate (the flag is set to "1").
1 "). The result of this determination is shown in FIG.

An arithmetic process is finally performed to determine the presence or absence of a defect.

FIG. 8 shows an outline of the arithmetic processing algorithm. The value (0 or 1) of the flag determined for each optical fiber is multiplied by a preset weighting factor to obtain the sum. When the sum is equal to or larger than a preset threshold value, it is determined that a defect exists. The weight coefficient is set for each optical fiber because there are parts to be particularly emphasized and parts that are not so important among the welded parts. Therefore, a large weighting factor is set for the determination result of the optical fiber of the portion to be emphasized, and a small weighting factor is set for the determination result of the optical fiber of the less important portion. When the laser power is changed, it is necessary to change the region of the welded portion to be monitored. For example, when the power of the laser is increased, a change is made to increase the weighting factor also for the determination result of the optical fiber in the outer region.

It should be noted that the welding state determination processing device 6 separately performs processing such as defect detection on the plurality of voltage signals from the photodiode 3 and the plurality of voltage signals from the photodiode 5 based on the above algorithm. If a defect is detected in one of the processes, an output indicating that there is a defect is performed.

(2) Evaluation of Weld Bead Size When the depth or width of the weld bead changes, the two-dimensional spread of welding light (reflected light of plasma light or irradiation laser light) also changes. From this, the size of the weld bead can be evaluated by determining the spread area of the welding light.

As shown in FIG. 9, the number of optical fibers for receiving the welding light changes depending on the change of the welding bead. Therefore, the correlation between the depth and width of the weld bead and the number of optical fibers received is determined in advance by experimental results. At the time of actual welding, the depth and width of the weld bead can be evaluated based on the number of optical fibers received based on the experimental results.

FIG. 10 shows three examples of the correlation between the depth and width of the weld bead and the number of optical fibers received.

The actual signal processing procedure will be described below.

A high-frequency component is removed from the signal after the A / D conversion processing by a digital low-pass filter processing. This is the same process as the defect detection in the above (1).

The predetermined threshold value c is compared with the level of the measurement signal. If the level is equal to or greater than the threshold value c, it is determined that the optical fiber has received light and counting is performed.

The depth and width of the weld bead are evaluated based on the experimental results from the number of optical fibers determined to have received light.

In the above description, a YAG laser oscillator is used as the laser oscillator.
For example, the present invention can be applied to a laser welding machine using a CO ₂ laser oscillator or an excimer laser oscillator. In this case, a configuration of an optical system and a photodiode, that is, a photoelectric conversion element are selected so that reflected light of the irradiation laser light can be detected.

[0048]

According to the present invention, the following effects can be obtained.

1. Welding light is divided into plasma light and reflected light of irradiation laser light, and the distribution of those is measured two-dimensionally and at multiple points. It is possible to evaluate the size (depth, width) of the weld bead.

2. Since the welding light can be measured coaxially with the irradiation laser light from above the laser torch, the defect can be detected even if the shape of the work is complicated.

3. From the above 1 and 2, the present invention can be applied to not only planar processing but also three-dimensional processing.

4. It can save labor and labor of inspectors and can shorten the inspection time by online measurement, which greatly contributes to automation of production lines (automated operation) by automated defect detection.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a laser welding machine according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining a relationship between an optical fiber and a photodiode shown in FIG.

FIG. 3 is a diagram for explaining a case where a visible / infrared CCD camera is used instead of the optical fiber and the photodiode shown in FIG. 1;

FIG. 4 is a block diagram illustrating a configuration of a welding state determination processing device illustrated in FIG. 1;

FIG. 5 is a waveform diagram showing an example of a measurement signal obtained from the optical fiber shown in FIG. 1 in a case where there is a defect.

FIG. 6 is a waveform diagram after a low-pass filter process is performed on the measurement signal shown in FIG. 5;

FIG. 7 is a diagram showing a result of discriminating presence / absence of a defect candidate from the signal shown in FIG. 6;

FIG. 8 is a diagram for explaining a defect detection processing algorithm performed using the determination result shown in FIG. 7;

FIG. 9 is a diagram showing an example of a two-dimensional distribution of welding light to the optical fiber in FIG. 1 for explaining a method of evaluating the size of a welding bead.

FIG. 10 is a diagram showing an example of a correlation between the depth and width of a weld bead and the number of light-receiving fibers of an optical fiber necessary for evaluating the size of the weld bead.

FIG. 11 is a diagram showing a configuration of a welding defect detection device already proposed by the present inventors.

12 is a diagram for explaining a problem in the welding defect detection device shown in FIG.

[Explanation of symbols]

 2, 4 Optical fiber 3, 5, 20, 24 Photodiode 21, 25 Amplifier 11 YAG laser oscillator 12 Laser torch 13 YAG laser reflection mirror 14 Work 15 Condensing lens 16 YAG light reflection mirror 17 YAG light cut filter 18 YAG light transmission band filter

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI H04N 5/335 G02B 7/18 Z (56) References JP-A-9-108866 (JP, A) JP-A-4-371381 ( JP, A) JP-A-11-138278 (JP, A) S. Mori et al., “Detection of welding defects in tailored blank welding”, Proceedings of the Japan Welding Society, Welding Society of Japan, November 5, 1996 Japan, Vol. 14, No. 4, p. 689-693 (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 26/00

Claims (10)

(57) [Claims] 1. A laser welding machine for performing welding by irradiating a laser beam to a work with a laser torch, wherein welding is performed in a housing of the laser torch so as to be coaxial with an optical axis of the laser light irradiated to the work. A condensing lens for condensing the reflected light of the plasma light and the laser light emitted from the location, for receiving the plasma light condensed by the condensing lens
Be received in the two-dimensional light-receiving means, the reflected light condensed laser beam by the condenser lens
And a two-dimensional light receiving means for the second order of the intensity of the reflected light of the received plasma light and laser light.
A laser welding machine for detecting a defect at a welding location based on a source distribution . 2. The laser welding machine according to claim 1, wherein
After the condenser lens, a first laser light reflecting mirror that reflects only the reflected light of the laser light and transmits the remaining light is provided, and a welding process is performed based on the transmitted light of the first laser light reflecting mirror. And a second filter for extracting only the reflected light of the laser light from the reflected light of the laser light reflecting mirror.
A laser welding machine comprising: a filter; 3. The laser welding machine according to claim 2, wherein
As the two-dimensional light receiving means, after the first filter, an optical fiber and a plurality of photoelectric conversion elements for photoelectrically converting light received by the optical fiber are arranged as a first group, and A laser welding machine , wherein an optical fiber and a plurality of photoelectric conversion elements for photoelectrically converting light received by the optical fiber are arranged as a second group even after the filter. 4. The laser welding machine according to claim 3, wherein
In the laser torch, there is provided a second laser light reflection mirror that reflects laser light from a laser transmission fiber connected to a laser oscillation source and irradiates the work toward the work, and the condensing lens includes the second laser light reflection mirror. 2. A laser welding machine, wherein the welding light emitted from the welding location is condensed through a second laser light reflecting mirror. 5. The laser welding machine according to claim 3, wherein
A determination processing device that detects a defect at a welding location based on the levels of a plurality of electric signals from the photoelectric conversion elements of the first group and the levels of a plurality of electric signals from the photoelectric conversion elements of the second group. The determination processing device determines whether the level of each of the plurality of electric signals is within a predetermined range for each of the first group and the second group, and "0" is output as a discrimination result when the value is within the predetermined range, and "1" is output as a discrimination result when the value is outside the predetermined range. A laser welding machine characterized in that the presence or absence of a defect is determined by comparing with a predetermined threshold value. 6. The laser welding machine according to claim 2, wherein
As the two-dimensional light receiving means, a first CCD camera capable of detecting visible light and infrared light is disposed after the first filter, and visible light and infrared light are also provided after the second filter. A laser welding machine comprising a second CCD camera capable of detecting a laser beam. 7. The laser welding machine according to claim 6, wherein
An image from the first CCD camera and the second CCD
A determination processing device that individually performs image processing on an image from a camera to detect a defect at a welding location, and the determination processing device includes:
The luminance level of each pixel from the first CCD camera (hereinafter, referred to as a first luminance level group) and the second
For each luminance level (hereinafter, referred to as a second luminance level group) for each pixel from the CCD camera,
It is determined whether or not each of the plurality of brightness levels is within a predetermined range, and “0” is determined when the brightness level is within the predetermined range, and “1” is determined when the brightness level is outside the predetermined range. A laser welding machine for outputting a result of the determination, performing a predetermined weighting on each determination result, and comparing the sum of the weighted values with a predetermined threshold value to determine the presence or absence of a defect. 8. The laser welding machine according to claim 5, wherein
The determination processing device may further include a welding bead size based on a level of the plurality of electric signals from the first group of photoelectric conversion elements and a level of the plurality of electric signals from the second group of photoelectric conversion elements. Evaluation means for evaluating whether the level of each of the plurality of electric signals is higher than a predetermined threshold value for each of the first group and the second group. A laser welding machine for determining and evaluating the depth and width of a weld bead based on the number of electrical signals higher than the preset threshold. 9. The laser welding machine according to claim 7, wherein
The determination processing device further includes evaluation means for evaluating the size of the weld bead from the first brightness level group and the second brightness level group, wherein the evaluation means includes the first brightness level group and the evaluation value. For each of the second brightness level groups, it is determined whether each of the plurality of brightness levels is higher than a predetermined threshold value, and the welding bead is determined based on the number of electrical signals higher than the predetermined threshold value. A laser welding machine characterized by evaluating the depth and width of a workpiece. The method according to claim 10 laser light when performing welding by irradiating a workpiece, in a housing of the laser torch, is irradiated to the workpiece
Emanating from the welding point set to be an optical axis coaxial with the laser beam, the reflected light of the plasma light and laser light condensed, the condensed plasma light, received by the two-dimensional light-receiving means, current The reflected light of the emitted laser light is used as two-dimensional light receiving means
From the intensity of the reflected light of the received plasma light and laser light
A laser welding state monitoring method, comprising detecting a defect at a welding location based on a source distribution .