JP7040949B2 - Parameter identification device, laser machine, parameter identification method, and program - Google Patents

Description

The present invention relates to a parameter specifying device, a laser machine, a parameter specifying method, and a program.

Patent Document 1 discloses a laser welding apparatus capable of capturing an image of a workpiece during laser welding and outputting the image to a monitor.
Further, Patent Document 2 discloses a technique for measuring the shape of a molten pool by imaging a workpiece and analyzing the image in laser welding. According to the technique described in Patent Document 1, the direction orthogonal to the welding direction is specified as the width direction of the molten pool, the length in the welding direction is specified as the length of the molten pool, and the length in the width direction is the molten pool. Specified as the width of. Parameters such as the length and width of the molten pool can be used to determine the quality of the weld.

Japanese Patent No. 6220718 Japanese Patent No. 3595511

In the technique disclosed in Patent Document 1, it is necessary that the welding direction is known in order to obtain the parameters of the molten pool. As a method of specifying the welding direction, for example, a method of specifying the welding direction from a numerical control device based on the time change of the relative coordinates of the workpiece and the head can be considered. However, when the welding direction is specified based on the time change, it is necessary to strictly synchronize the camera image with the information acquired from the numerical control device, and there is a problem that a time delay occurs due to the relative coordinate acquisition cycle. There is.
An object of the present invention is to provide a parameter specifying device, a laser machine, a parameter specifying method, and a program capable of specifying the parameters of a molten pool regardless of whether or not the welding direction is specified.

According to the first aspect of the present invention, the parameter specifying device includes an image acquisition unit that acquires a molten pool image in which a molten pool generated by irradiating a workpiece with a processing laser is irradiated, and an image of the molten pool. Of these, parameters that specify the parameters of the molten pool based on the brightness of the pixels for each radius or angle with the melting center, which is the position where the optical axis of the processing laser intersects, as the origin of the coordinates. It has a specific part.

According to the second aspect of the present invention, the parameter specifying device according to the first aspect further includes a polar coordinate conversion unit that converts an image into polar coordinates, and the parameter specifying unit is based on the image that has been polar coordinate converted. It may specify a parameter.

According to the third aspect of the present invention, the parameter specifying device according to the first or second aspect further includes a binarizing unit for binarizing the image, and the parameter specifying unit is binarized. The parameter may be specified based on the image.

According to the fourth aspect of the present invention, in the parameter specifying device according to any one of the first to third aspects, the parameter specifying unit specifies the length of the molten pool as the parameter. good.

According to the fifth aspect of the present invention, in the parameter specifying device according to the fourth aspect, the parameter specifying unit has the minimum radius length at which the sum of the brightness of the pixels for each radius is equal to or less than a predetermined threshold value. The length may be specified based on the radius.

According to the sixth aspect of the present invention, in the parameter specifying device according to any one of the first to fifth aspects, the parameter specifying unit may specify the width of the molten pool as the parameter. ..

According to the seventh aspect of the present invention, in the parameter specifying device according to the sixth aspect, the parameter specifying unit specifies the width based on the minimum value of the sum of the brightness of the pixels for each declination. It may be there.

According to the eighth aspect of the present invention, the laser processing machine captures a laser nozzle, a laser oscillator that irradiates a processing laser through the laser nozzle, and a molten pool image in which the molten pool is captured via the laser nozzle. An image pickup device for taking an image and a parameter specifying device according to any one of the first to sixth aspects are provided.

According to the ninth aspect of the present invention, the parameter specifying method includes a step of acquiring a molten pool image in which a molten pool generated by irradiating a work piece with a processing laser is performed , and the above -mentioned molten pool image. A step of specifying the parameters of the molten pool based on the brightness of the pixel for each radius or for each deviation angle with the melting center at the position where the melting pond and the optical axis of the processing laser intersect as the origin of the coordinates. include.

According to the tenth aspect of the present invention, the program includes a step of acquiring a molten pool image in which a molten pool generated by irradiating a work piece with a processing laser is performed on a computer, and among the molten pool images. With the step of specifying the parameters of the molten pool based on the brightness of the pixel for each moving diameter or for each deviation angle with the melting center at the position where the optical axis of the molten pool intersects with the optical axis of the processing laser as the origin of the coordinates. To execute.

According to at least one of the above embodiments, the parameters of the molten pool can be specified regardless of whether or not the welding direction is specified.

It is an external view of the laser processing machine which concerns on 1st Embodiment. It is a schematic diagram which shows the structure of the laser processing machine which concerns on 1st Embodiment. It is a schematic block diagram which shows the structure of the evaluation apparatus which concerns on 1st Embodiment. It is a figure which shows the example of the molten pool image. It is a figure which shows the example of the binary polar coordinate image. It is a flowchart which shows the evaluation method by the evaluation apparatus which concerns on 1st Embodiment. It is a histogram which shows the number of the pixel which shows the brightness 1 about the declination angle of a binary polar coordinate image. It is a histogram which shows the number of the pixel which shows the brightness 1 about the radius of a binary polar coordinate image. It is a figure which shows the relationship between the binary molten pool image and the parameter of a molten pool. It is an external view of the laser processing machine which concerns on 2nd Embodiment. It is a schematic block diagram which shows the structure of the evaluation apparatus which concerns on 2nd Embodiment. It is a flowchart which shows the control method by the correction apparatus which concerns on 2nd Embodiment.

<First Embodiment>
<< Configuration of laser processing machine >>
Hereinafter, embodiments will be described in detail with reference to the drawings.
FIG. 1 is an external view of the laser processing machine according to the first embodiment.
The laser processing machine 1 performs laser processing by irradiating the workpiece W with a processing laser. An example of laser machining is welding.
The laser processing machine 1 includes a stage 101, a head 102, a support portion 103, a numerical control device 104, and an evaluation device 105.

The stage 101 is a table for fixing the workpiece W. The stage 101 is provided with a drive mechanism such as an actuator, whereby the stage 101 is configured to be movable in the horizontal direction (X-axis-Y-axis direction). The head 102 irradiates the machining laser toward the workpiece W on the stage 101. The head 102 is provided with a laser nozzle 1021 through which a processing laser and an assist gas pass. The support portion 103 supports the head 102. The numerical control device 104 controls the position of the head 102 and the output conditions of the processing laser (ON / OFF of the processing laser, output value, beam diameter, etc.) according to the operation of the user or the program specified by the user. .. The evaluation device 105 identifies and displays the parameters of the molten pool related to the laser processing by the laser processing machine 1. The user of the laser processing machine 1 visually recognizes the parameters displayed by the evaluation device 105, and adjusts the laser processing so that the parameters approach the target value. The evaluation device 105 is an example of a parameter specifying device.

FIG. 2 is a schematic view showing the configuration of the laser processing machine according to the first embodiment.
The laser processing machine 1 includes a laser oscillator 106, an image pickup device 107, a lighting device 108, and an optical system 109.
The laser oscillator 106 outputs a processing laser via the optical system 109. The image pickup apparatus 107 images the workpiece W on the stage 101 via the optical system 109. The lighting device 108 emits illumination light for imaging by the image pickup device 107.

The optical system 109 includes a prism 1091, a dichroic mirror 1092, a condenser lens 1093, a half mirror 1094, a first total reflection mirror 1095, and a second total reflection mirror 1096.
The prism 1091 is provided on the optical axis of the processing laser output by the laser oscillator 106. The dichroic mirror 1092 is provided on the optical axis of the processing laser and after the prism 1091. The dichroic mirror 1092 reflects the processing laser so that it passes through the laser nozzle 1021. The condenser lens 1093 is provided on the optical axis of the processing laser, after the processing laser and in front of the laser nozzle 1021 from the dichroic mirror 1092.
That is, after being output from the laser oscillator 106, the processing laser passes through the optical system 109 in the order of the prism 1091, the dichroic mirror 1092, and the condenser lens 1093, and passes through the laser nozzle 1021 to the workpiece W on the stage 101. Be irradiated.

The first total reflection mirror 1095 is provided on the optical axis of the image pickup apparatus 107. The first total reflection mirror 1095 is provided in such a posture that the optical axis of the image pickup apparatus 107 passes through the dichroic mirror 1092 and the laser nozzle 1021. That is, the optical axis of the image pickup apparatus 107 and the optical axis of the processing laser coincide with each other between the dichroic mirror 1092 and the workpiece W by the first total reflection mirror 1095.

The half mirror 1094 is provided on the optical axis of the image pickup device 107 and between the first total reflection mirror 1095 and the image pickup device 107. The second total reflection mirror 1096 is provided on the optical axis of the lighting device 108. The second total reflection mirror 1096 is provided in such a posture that the illumination light emitted from the illumination device 108 is reflected by the half mirror 1094 and passes through the dichroic mirror 1092 and the laser nozzle 1021.
That is, the illumination light emitted by the illuminating device 108 passes through the optical system 109 in the order of the second full reflection mirror 1096, the half mirror 1094, the first full reflection mirror 1095, the dichroic mirror 1092, and the condenser lens 1093, and is on the stage 101. The workpiece W is irradiated. Then, the illumination light reflected by the workpiece W passes through the optical system 109 in the order of the condenser lens 1093, the dichroic mirror 1092, the first full reflection mirror 1095, and the half mirror 1094, and reaches the image pickup apparatus 107.
With the above configuration, the image pickup apparatus 107 can image the focal position of the processing laser via the laser nozzle 1021.

When the workpiece W is laser-machined by the machining laser, a molten pool is formed in the workpiece W. At this time, since the optical axis of the image pickup device 107 and the optical axis of the processing laser coincide with each other due to the above configuration, the melting center of the molten pool in the image captured by the image pickup device 107 is always located at the center of the image.

<< Configuration of evaluation device >>
FIG. 3 is a schematic block diagram showing the configuration of the evaluation device according to the first embodiment.
The evaluation device 105 includes a processor 151, a main memory 152, a storage 153, and an interface 154. The processing evaluation program is stored in the storage 153. The processor 151 reads the machining evaluation program from the storage 153, expands it in the main memory 152, and executes the laser machining evaluation process according to the machining evaluation program. Further, the processor 151 secures a predetermined storage area in the main memory 152 according to the machining evaluation program.

Examples of the storage 153 include HDD (Hard Disk Drive), SSD (Solid State Drive), magnetic disk, magneto-optical disk, CD-ROM (Compact Disc Read Only Memory), and DVD-ROM (Digital Versatile Disc Read Only Memory). , Semiconductor memory and the like. The storage 153 may be an internal medium directly connected to the bus of the evaluation device 105, or an external medium connected to the evaluation device 105 via the interface 154 or a communication line. When this program is distributed to the evaluation device 105 by a communication line, the distributed evaluation device 105 may expand the program to the main memory 152 and execute the above processing. In at least one embodiment, the storage 153 is a non-temporary tangible storage medium.

An input device 110, an output device 111, an image pickup device 107, and a numerical control device 104 are connected to the interface 154. Examples of the input device 110 include a keyboard, a mouse, a touch panel, and the like. Examples of the output device 111 include a display, a projector, a printer, and the like.

The processor 151 functions as an image acquisition unit 1511, a polar coordinate conversion unit 1512, a binarization unit 1513, a parameter specification unit 1514, and a display control unit 1515 by executing a processing evaluation program stored in the storage 153.
The image acquisition unit 1511 acquires an image captured by the image pickup apparatus 107. The image is a molten pool image showing the molten pool. FIG. 4 is a diagram showing an example of a molten pool image. The work piece W emits stronger light due to heat radiation as the temperature rises. Therefore, as shown in FIG. 4, the brightness of the portion where the molten pool is reflected in the molten pool image is higher than that of the other portions.
The polar coordinate conversion unit 1512 generates a polar coordinate image by performing polar coordinate conversion of the molten pool image with the position where the melting center of the molten pool image is captured as the origin. A polar coordinate image is a set of pixels mapped to a polar coordinate plane consisting of an argument axis and a radial axis.
The binarization unit 1513 binarizes the polar coordinate image generated by the polar coordinate conversion unit 1512 to generate a binary polar coordinate image. The binarization unit 1513 determines whether or not the brightness of each pixel of the polar coordinate image is equal to or higher than a predetermined threshold value, 1 is the brightness of the pixel whose brightness is equal to or higher than the threshold value, and 0 is the brightness of the pixel whose brightness is lower than the threshold value. To decide. FIG. 5 is a diagram showing an example of a binary polar coordinate image. The binary polar coordinate image shown in FIG. 5 is an image in which the vertical axis has a declination and the horizontal axis has a radius.
The parameter specifying unit 1514 specifies the parameters (length and width) of the molten pool of the workpiece W based on the binary polar coordinate image generated by the binarizing unit 1513.
The display control unit 1515 displays the parameters of the molten pool specified by the parameter specifying unit 1514.

"Evaluation methods"
When the workpiece W is installed on the stage 101, the user inputs to the evaluation device 105 an instruction to start the evaluation process of the molten pool parameter from the user via the input device 110. Then, the user operates the laser processing machine 1 via the numerical control device 104.
The image pickup apparatus 107 captures a molten pool image at regular time intervals (for example, 100 milliseconds). The evaluation device 105 executes the following evaluation process each time the image pickup device 107 captures a molten pool image.

FIG. 6 is a flowchart showing an evaluation method by the evaluation device according to the first embodiment.
The image acquisition unit 1511 of the evaluation device 105 acquires a molten pool image from the image pickup device 107 (step S1). The polar coordinate conversion unit 1512 converts the molten pond image into polar coordinates around the coordinates in which the molten center of the acquired molten pool image is captured, and generates a polar coordinate image (step S2). As shown in FIG. 2, since the optical axis of the image pickup apparatus 107 coincides with the optical axis of the processing laser, the melting center is always located at the same coordinates of the molten pool image (for example, the center coordinates of the image).

Next, the binarization unit 1513 binarizes the polar coordinate image and generates a binary polar coordinate image (step S3). The brightness threshold used for binarization by the binarization unit 1513 may be, for example, a predetermined value associated with the processing conditions, or may be the beam diameter obtained from the settings of the laser oscillator 106 and the optical system 109. It may be determined based on, or it may be determined according to the standard deviation of the brightness distribution of the molten pool image or the polar coordinate image.

FIG. 7 is a histogram showing the number of pixels showing a brightness of 1 with respect to the declination angle of the binary polar coordinate image. FIG. 8 is a histogram showing the number of pixels having a brightness of 1 for the radius of the binary polar coordinate image. FIG. 9 is a diagram showing the relationship between the binary molten pool image and the parameters of the molten pool.
Next, the parameter specifying unit 1514 calculates the number of pixels having a brightness of 1 for each declination of the binary polar coordinate image (step S4). Hereinafter, a pixel having a brightness of 1 is also referred to as a bright pixel. That is, the parameter specifying unit 1514 calculates the histogram shown in FIG. 7. The parameter specifying unit 1514 specifies the minimum value among the calculated number of bright pixels (step S5). That is, the parameter specifying unit 1514 specifies the number of bright pixels r1 at the declination that minimizes the number of bright pixels. The parameter specifying unit 1514 specifies a length corresponding to twice the specified number of bright pixels r1 as the width W of the molten pool (step S6).
As described above, since the brightness of the pixel in which the molten pool is reflected in the molten pool image is higher than the brightness of the other pixels, the pixel corresponding to a part of the molten pool is a bright pixel in the binary pole coordinate image. Therefore, as shown in FIG. 9, the minimum value of the number of bright pixels is a circle whose origin is the melting center and corresponds to the radius r1 of the maximum circle containing only the bright pixels. As shown in FIG. 9, the width W of the molten pool substantially coincides with the diameter of such a circle.

Next, the parameter specifying unit 1514 calculates the number of bright pixels for each radius of the binary polar coordinate image (step S7). That is, the parameter specifying unit 1514 calculates the histogram shown in FIG. The parameter specifying unit 1514 specifies a minimum radius value r2 in which the number of bright pixels is equal to or less than a predetermined threshold value (for example, 0) (step S8). The parameter specifying unit 1514 calculates the sum of the number of bright pixels r1 calculated in step S4 and the specified radius r2 as the length L of the molten pool (step S9).
As described above, since the brightness of the pixel in which the molten pool is reflected in the molten pool image is higher than the brightness of the other pixels, the pixel corresponding to a part of the molten pool is a bright pixel in the binary pole coordinate image. Therefore, as shown in FIG. 9, the minimum radius value at which the number of pixels showing a brightness of 1 is equal to or less than a predetermined threshold value is a circle having the melting center as the origin and the minimum including the melting pond. Corresponds to the radius r2 of the circle.

The display control unit 1515 causes the output device 111 to output the width W and the length L of the molten pool specified by the parameter specifying unit 1514 (step S10). The user adjusts the laser processing so that these values approach the target values of the width and length of the molten pool while observing the width W and the length L of the molten pool output to the output device 111. For example, if the length of the molten pool is longer than the target value, the user slows down the sweep speed of the head 102, and if the length of the molten pool is shorter than the target value, the user speeds up the sweep speed of the head 102. For example, if the width of the molten pool is wider than the target value, the user narrows the beam diameter of the processing laser, and if the width of the molten pool is narrower than the target value, the user widens the beam diameter of the processing laser.

《Action / Effect》
As described above, the evaluation device 105 according to the first embodiment specifies the parameters of the molten pool based on the brightness of the pixels for each radius or each deviation angle centered on the coordinates of the center of the molten pool in the molten pool image. .. The evaluation device 105 can specify the parameters of the molten pool regardless of whether or not the welding direction is specified by specifying the parameters of the molten pool based on the moving diameter or the deviation angle of the molten pool image. Specifically, according to the polar coordinate image as shown in FIG. 5, when the welding direction changes, the image shifts in the vertical direction. This is because the declination at which the peak portion occurs changes due to the change in the welding direction. That is, even if the welding direction changes, there is no change related to rotation in the polar coordinate image. Therefore, the evaluation device 105 can specify the parameters of the molten pool regardless of whether or not the welding direction is specified by specifying the parameters of the molten pool based on the radial diameter or the deviation angle of the molten pool image.

Further, the evaluation device 105 according to the first embodiment binarizes the polar coordinate image to obtain the parameters of the molten pool. By binarizing the polar coordinate image, the evaluation device 105 can directly convert the number of bright pixels for each declination into the length. Further, the evaluation device 105 can remove noise contained in the image by binarizing the image. That is, the evaluation device 105 can easily and accurately obtain the parameters of the molten pool by binarizing the polar coordinate image.
In another embodiment, the evaluation device 105 may obtain the parameters of the molten pool without performing the binarization process. For example, when the brightness takes a value in the range of 0 to 255, the parameter specifying unit 1514 of the evaluation device 105 takes the total brightness of the pixels for each deviation angle or each radius, and the total brightness is set as the length. The parameters of the molten pool may be obtained by conversion. Since the brightness of the pixels in the binary image indicates 1 or 0, the number of bright pixels in the binary image is equal to the total brightness of the pixels.

Further, the evaluation device 105 according to the first embodiment specifies the width and length of the molten pool as parameters of the molten pool. The width and length of the molten pool are known to be related to the penetration depth of the weld. It is also known that if the width of the molten pool is too large, welding deformation and residual stress are likely to increase. Therefore, when the evaluation device 105 specifies the width and length of the molten pool as the parameters of the molten pool and presents them to the user, the user can easily improve the quality of welding.

Further, the evaluation device 105 according to the first embodiment specifies the length of the molten pool based on the length of the minimum radius at which the number of bright pixels of the binary polar coordinate image is equal to or less than a predetermined threshold value. That is, the evaluation device 105 specifies the melt length based on the length of the minimum radius at which the sum of the brightness of the pixels for each radius is equal to or less than a predetermined threshold value. As a result, the evaluation device 105 is used even when a part of the molten pool appears dark in the molten pool image, that is, when a dark pixel is partially included in the molten pool portion of the binary pole coordinate image. Also, the length of the molten pool can be appropriately specified. Further, the evaluation device 105 includes bright pixels in a part of the non-molten pond portion of the binary pole coordinate image, that is, even when the portion away from the molten pool is brightly reflected in the molten pool image due to spatter or the like. Even in such a case, the length of the molten pool can be appropriately specified. It should be noted that the present invention is not limited to this in other embodiments. For example, the evaluation device 105 may specify the length of the molten pool based on the maximum value of the sum of the brightness of the pixels for each declination.

Further, the evaluation device 105 according to the first embodiment specifies the width of the molten pool based on the minimum value of the number of bright pixels for each declination of the binary polar coordinate image. That is, the evaluation device 105 specifies the width of the molten pool based on the minimum value of the sum of the brightness of the pixels for each declination of the binary polar coordinate image. It should be noted that the present invention is not limited to this in other embodiments. For example, the evaluation device 105 may specify the melt length based on the length of the maximum radius at which the sum of the brightness of the pixels for each radius is equal to or greater than a predetermined threshold value.

<< Second Embodiment >>
In the laser processing machine 1 according to the first embodiment, the evaluation device 105 displays the parameters of the molten pool to improve the quality of welding in manual operation. On the other hand, the laser processing machine 1 according to the second embodiment aims to improve the quality of welding in the automatic operation based on the parameters of the molten pool.

<< Configuration of laser processing machine >>
FIG. 10 is an external view of the laser processing machine according to the second embodiment.
The laser processing machine 1 according to the second embodiment includes a correction device 201 instead of the evaluation device 105 of the first embodiment. The correction device 201 identifies the parameters of the molten pool related to the laser processing by the laser processing machine 1, and corrects the control parameters of the numerical control device 104 based on the parameters. The correction device 201 is an example of a parameter specifying device.

<< Configuration of correction device >>
FIG. 11 is a schematic block diagram showing the configuration of the evaluation device according to the second embodiment.
The correction device 201 includes a processor 151, a main memory 152, a storage 153, and an interface 154, similarly to the evaluation device 105 of the first embodiment.
The processor 151 functions as an image acquisition unit 1511, a polar coordinate conversion unit 1512, a binarization unit 1513, a parameter specifying unit 1514, and a correction unit 1516 by executing a correction program stored in the storage 153. Further, by executing the correction program, the storage area of the target value storage unit 1521 is secured in the main memory 152.

The correction unit 1516 corrects the control parameters of the numerical control device 104 based on the parameters of the molten pool specified by the parameter specifying unit 1514.
The target value storage unit 1521 stores the target value of each parameter of the molten pool.

<< Control method >>
When the workpiece W is installed on the stage 101, the user sets the mode of the numerical control device 104 to the mode for performing automatic operation by the program. Then, the user operates the input device 110 and inputs an instruction to start the correction process to the correction device 201.
The image pickup apparatus 107 captures a molten pool image at regular time intervals (for example, 100 milliseconds). The correction device 201 executes the following correction processing each time the image pickup device 107 captures a molten pool image.

FIG. 12 is a flowchart showing a control method by the correction device according to the second embodiment.
The image acquisition unit 1511 of the correction device 201 acquires a molten pool image from the image pickup device 107 (step S101). The polar coordinate conversion unit 1512 converts the molten pond image into polar coordinates around the coordinates in which the molten center of the acquired molten pool image is captured, and generates a polar coordinate image (step S102). The binarization unit 1513 binarizes the polar coordinate image and generates a binary polar coordinate image (step S103).

The parameter specifying unit 1514 calculates the number of bright pixels for each declination of the binary polar coordinate image (step S104). The parameter specifying unit 1514 specifies the minimum value among the calculated number of bright pixels (step S105). The parameter specifying unit 1514 specifies a length corresponding to twice the specified number of bright pixels as the width of the molten pool (step S106).

The parameter specifying unit 1514 calculates the number of bright pixels for each radius of the binary polar coordinate image (step S107). The parameter specifying unit 1514 specifies the value of the minimum radius at which the number of bright pixels is equal to or less than a predetermined threshold value (step S108). The parameter specifying unit 1514 calculates the sum of the number of bright pixels calculated in step S104 and the specified radius as the length of the molten pool (step S109).

The correction unit 1516 calculates the ratio between the specified parameter and the target value stored in the target value storage unit 1521 (step S110). That is, the correction unit 1516 calculates the ratio between the target value of the width of the molten pool stored in the target value storage unit 1521 and the width of the molten pool. Further, the correction unit 1516 calculates the ratio between the target value of the length of the molten pool stored in the target value storage unit 1521 and the length of the molten pool.
The correction unit 1516 obtains a correction coefficient for the control parameter of the numerical control device 104 based on the ratio of the parameter to the target value (step S111). Specifically, the correction unit 1516 determines the sweep speed of the head 102, the beam diameter of the processing laser, that is, the optical system 109, based on the ratio of the width of the molten pool to the target value and the ratio of the length of the molten pool to the target value. And the correction coefficient of the output intensity of the laser oscillator 106 are obtained. The relationship between the ratio of the parameter to the target value and the correction coefficient of the control parameter of the numerical control device 104 has been obtained in advance by an experiment or the like.
The correction unit 1516 outputs the specified correction coefficient to the numerical control device 104 (step S12).

The numerical control device 104 changes the control parameters according to the correction coefficient. Thereby, the numerical control device 104 can control the laser processing machine 1 so that the parameter of the molten pool approaches the target value.

<Other embodiments>
Although one embodiment has been described in detail with reference to the drawings, the specific configuration is not limited to the above-mentioned one, and various design changes and the like can be made.
For example, in the above-described embodiment, the evaluation device 105 or the correction device 201, which is a parameter specifying device, is provided separately from the numerical control device 104, but the present invention is not limited to this. For example, in another embodiment, the numerical control device 104 may be equipped with a function as a parameter specifying device.

Further, in the above-described embodiment, the optical axis of the image pickup apparatus 107 and the optical axis of the processing laser are aligned, but the present invention is not limited to this. For example, the image pickup apparatus 107 may be attached to the outside of the head 102. In this case, unlike the above-described embodiment, the melting center of the molten pool is not always located at the same coordinates in the molten pool image. In this case, the parameter specifying device may specify the melting center by the following method.
The parameter identification device binarizes the molten pool image while increasing the brightness threshold. The parameter specifying device identifies the coordinates of the center of the circle as the melting center when the outer shape of the group of bright pixels reflected in the binary image becomes a substantially circular shape. This is because the temperature of the center of the molten pool irradiated with the processing laser is higher than the temperature of the other parts of the molten pool, and the intensity of synchrotron radiation is stronger than that of the other parts.

1 Laser processing machine 104 Numerical control device 105 Evaluation device 106 Laser oscillator 107 Image pickup device 110 Input device 111 Output device 201 Correction device 1511 Image acquisition unit 1512 Polar coordinate conversion unit 1513 Binarization unit 1514 Parameter specification unit 1515 Display control unit 1516 Correction unit 1521 Target value storage unit

Claims (10)

An image acquisition unit that acquires a molten pool image that captures the molten pool generated by irradiating the workpiece with a laser for processing .
In the molten pool image, the molten pool is based on the brightness of the pixels for each radius or angle with the melting center at the position where the optical axis of the processing laser intersects as the origin of the coordinates. A parameter identification device having a parameter identification unit for specifying parameters. It also has a polar coordinate conversion unit that converts images into polar coordinates.
The parameter specifying device according to claim 1, wherein the parameter specifying unit specifies the parameter based on the image transformed into polar coordinates. It also has a binarization section that binarizes the image.
The parameter specifying device according to claim 1 or 2, wherein the parameter specifying unit specifies the parameter based on the binarized image. The parameter specifying device according to any one of claims 1 to 3, wherein the parameter specifying unit specifies the length of the molten pool as the parameter. The parameter specifying device according to claim 4, wherein the parameter specifying unit specifies the length based on the length of the minimum radius at which the sum of the brightness of the pixels for each radius is equal to or less than a predetermined threshold value. The parameter specifying device according to any one of claims 1 to 5, wherein the parameter specifying unit specifies the width of the molten pool as the parameter. The parameter specifying device according to claim 6, wherein the parameter specifying unit specifies the width based on the minimum value of the sum of the brightness of the pixels for each declination angle. Laser nozzle and
A laser oscillator that irradiates a processing laser through the laser nozzle,
An image pickup device that captures an image of a molten pool in which the molten pool is captured via the laser nozzle.
A laser processing machine including the parameter specifying device according to any one of claims 1 to 7 . The step of acquiring a molten pool image showing the molten pool generated by irradiating the workpiece with a laser for processing, and
In the molten pool image, the molten pool is based on the brightness of the pixels for each radius or angle with the melting center at the position where the optical axis of the processing laser intersects as the origin of the coordinates. A parameter identification method that includes steps to identify the parameter. On the computer
The step of acquiring a molten pool image showing the molten pool generated by irradiating the workpiece with a laser for processing, and
In the molten pool image, the molten pool is based on the brightness of the pixels for each radius or angle with the melting center at the position where the optical axis of the processing laser intersects as the origin of the coordinates. A program for performing steps and executions that specify parameters.

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