Laser processing machine and method for detecting soiling of protection glass

Abstract

To provide a laser processing machine capable of detecting soiling of a protection glass in a line (during processing).SOLUTION: A laser processing machine 1 includes: a camera 5 that captures an image of radiation light emitted from a processing point of a sheet metal W when a laser beam is radiated from a processing head 3 to the sheet metal W to cut the sheet metal W; and a control unit 7 that detects soiling of a protection glass 27 provided on the processing head 3 on the basis of the image of the radiation light captured by the camera 5. The control unit 7 determines whether or not the protection glass 27 is soiled on the basis of a gap between the radiation light and the sheet metal W on the captured image.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a laser processing machine and a method for detecting dirt on a protective glass. [Background technology]

[0002] Patent document 1 describes an apparatus for inspecting the condition of protective glass in relation to laser machining. In the apparatus described in Patent document 1, a photodetector is arranged on the edge of the protective glass to detect radiation scattered by dust particles on the surface of the protective glass. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2001-509889 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned conventional device, the protective glass is inspected using a measurement laser beam that is different from the laser beam used in the laser processing. Therefore, the conventional device has a problem that it cannot detect dirt on the protective glass in-line (during processing). [Means for solving the problem]

[0005] A laser processing machine according to one embodiment of the present invention comprises a camera that captures the radiation light emitted from the processing point of the sheet metal when a laser beam is irradiated from the processing head to cut the sheet metal, and a control unit that detects dirt on a protective glass provided on the processing head based on the radiation light captured by the camera, and the control unit determines whether the protective glass is dirty or not based on the gap between the radiation light and the sheet metal on the captured image.

[0006] Another aspect of the present invention relates to a method for detecting dirt on a protective glass, in which when a laser beam is irradiated from the processing head of a laser processing machine to cut sheet metal, the radiation light emitted from the processing point of the sheet metal is captured by a camera, and whether or not the protective glass provided on the processing head is dirty is determined based on the gap between the radiation light and the sheet metal in the captured image.

[0007] According to the laser processing machine and the method for detecting dirt on a protective glass according to one aspect of the present invention, whether or not the protective glass is dirty is determined based on the gap between the radiated light and the metal sheet, so that the dirt on the protective glass can be detected while monitoring the processing state of the metal sheet. Therefore, it is possible to detect the dirt on the protective glass in-line (during processing). Effect of the Invention

[0008] According to one aspect of the invention, contamination of the protective glass can be detected in-line (during processing). [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a configuration of a laser processing machine according to an embodiment. [Figure 2A] FIG. 2A is a diagram showing an example of a captured image when there is no dirt on the protective glass of the laser processing machine according to one embodiment. [Figure 2B] FIG. 2B is a diagram showing a state of the protective glass of the laser processing machine according to one embodiment when the protective glass is not dirty. [Figure 3A] FIG. 3A is a diagram showing an example of a captured image when the dirt on the protective glass of the laser processing machine according to one embodiment is small. [Figure 3B] FIG. 3B is a diagram showing a state of the protective glass of the laser processing machine according to one embodiment when the dirt on the protective glass is small. [Figure 4A] FIG. 4A is a diagram showing an example of a captured image when the protective glass of the laser processing machine according to one embodiment is moderately dirty. [Figure 4B]FIG. 4B is a diagram showing a state of the protective glass of the laser processing machine according to one embodiment when the protective glass is moderately dirty. [Figure 5A] FIG. 5A is a diagram showing an example of a captured image when the protective glass of the laser processing machine according to one embodiment is heavily soiled. [Figure 5B] FIG. 5B is a diagram showing a state of the protective glass of the laser processing machine according to one embodiment when the protective glass is heavily soiled. [Figure 6] FIG. 6 is a diagram showing an example of a captured image when a lighting device is not installed in the laser processing machine according to one embodiment. [Figure 7] FIG. 7 is a flowchart showing a procedure of a process for detecting dirt on a protective glass by a laser processing machine according to an embodiment. [Figure 8] FIG. 8 is a diagram for explaining a method for measuring the length of the gap when the protective glass is not dirty, using a laser processing machine according to one embodiment. [Figure 9] FIG. 9 is a diagram for explaining a method for measuring the length of the gap when the protective glass is highly contaminated by the laser processing machine according to one embodiment. [Figure 10] FIG. 10 is a diagram showing the relationship between the gap length and the threshold value in a laser processing machine according to one embodiment. [Figure 11A] FIG. 11A is an example of an image captured by enlarging a cut portion of a metal sheet when there is no dirt on the protective glass of the laser processing machine according to one embodiment. [Figure 11B] FIG. 11B is an example of an image captured by enlarging a cut portion of a metal sheet when the protective glass of the laser processing machine according to one embodiment is heavily soiled. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Laser processing machine configuration] Hereinafter, a laser processing machine and a method for detecting dirt on a protective glass according to the present embodiment will be described with reference to the drawings. FIG. 1 is a diagram showing the configuration of a laser processing machine. As shown in FIG. 1, the laser processing machine 1 includes a processing head 3, a camera 5, a control unit 7, a laser oscillator 9, and an illumination device 11. The laser processing machine 1 is a device that emits a laser beam from the laser oscillator 9 to perform laser cutting on a metal sheet metal W.

[0011] The laser processing machine 1 includes a camera 5 that captures an image of radiation light emitted from a processing point on the metal sheet W when the metal sheet W is cut by irradiating a laser beam from the processing head 3, and a control unit 7 that detects dirt on a protective glass 27 provided on the processing head 3 based on the radiation light captured by the camera 5. The control unit 7 determines whether or not the protective glass 27 is dirty based on a gap between the radiation light and the metal sheet W on the captured image.

[0012] The processing head 3 is connected to a laser oscillator 9 via a transmission fiber, and irradiates a laser beam emitted from the laser oscillator 9 toward the metal sheet W. Inside the processing head 3, a camera 5, a bandpass filter 13, an imaging lens 15, collimating lenses 17 and 19, a beam splitter 21, a bend mirror 23, a focusing lens 25, and a protective glass 27 are provided.

[0013] The camera 5 is disposed at the upper end inside the processing head 3, and captures an image of the radiation light emitted from the processing point of the metal sheet W. When the metal sheet W is irradiated with a laser beam and radiation light is emitted from the processing point, the radiation light enters the camera 5 via the bandpass filter 13 and the imaging lens 15. At this time, the bandpass filter 13 transmits light of a specific wavelength band, and the imaging lens 15 is moved vertically to adjust the focus of the camera 5. The image captured in this manner is output to the control unit 7.

[0014] The laser oscillator 9 is a fiber laser oscillator or a YAG laser oscillator, etc., and oscillates a laser beam and supplies it to the processing head 3. The laser beam supplied from the laser oscillator 9 is converted into parallel light (collimated light) by the collimating lens 19, reflected by the bend mirror 23 and bent 90 degrees in its traveling direction, focused by the focusing lens 25, and transmitted through the protective glass 27 to be irradiated onto the metal sheet W.

[0015] The lighting device 11 is composed of a plurality of light-emitting diodes (LEDs) and irradiates the metal sheet W with illumination light. The illumination light irradiated from the lighting device 11 is converted into parallel light (collimated light) by the collimator lens 17, reflected by the beam splitter 21 and bent 90 degrees in its traveling direction, and transmitted through the focusing lens 25 and protective glass 27 to be irradiated onto the metal sheet W.

[0016] The protective glass 27 is provided at the tip of the processing head 3, and is disposed between the focusing lens 25 and the metal sheet W. The protective glass 27 prevents spatters generated during laser processing and dust in the air from adhering to the focusing lens 25.

[0017] The control unit 7 executes a process for detecting dirt on the protective glass 27 provided on the processing head 3 based on the radiation light captured by the camera 5. Specifically, the control unit 7 determines whether or not the protective glass 27 is dirty based on the gap between the radiation light and the metal sheet W on the captured image.

[0018] Fig. 2A is a diagram showing an example of a captured image when there is no dirt on the protective glass 27, and Fig. 2B is a diagram showing the state of the protective glass 27 when there is no dirt on the protective glass 27. As shown in Fig. 2A, the camera 5 captures an image of a processing point where the metal sheet W is irradiated with a laser beam, and the captured image captures the metal sheet W reflecting light from the lighting device 11 and the radiant light 31 emitted when the metal sheet W is heated by the laser beam and reaches a high temperature.

[0019] On the sheet metal W that is actually being machined, a kerf 33 is formed around the synchrotron light 31. On the other hand, on the captured image, there is a gap between the synchrotron light 31 and the sheet metal W at the portion of the kerf 33. This gap is a gap between the synchrotron light 31 and the sheet metal W formed at the portion of the kerf 33 on the captured image, and is a dark region between the synchrotron light 31 and the sheet metal W as shown in FIG. 2A.

[0020] The control unit 7 measures the lengths of gaps 34L and 34R located on the left and right of the center 31A of the radiation light corresponding to the center of the laser beam, among the gaps around the radiation light 31. In Fig. 2A, the lengths of the gaps 34L and 34R are approximately the same, and are shorter than when the protective glass 27, which will be described later, is dirty. The lengths of the gaps 34L and 34R are the lengths of the gaps located in a direction perpendicular to the traveling direction of the laser beam at the position of the center 31A of the radiation light.

[0021] Fig. 3A is a diagram showing an example of a captured image when the dirt on protective glass 27 is small, and Fig. 3B is a diagram showing the state of protective glass 27 when the dirt on protective glass 27 is small. As shown in Fig. 3B, when a small stain is attached to protective glass 27, the length of gap 34L remains short as shown in Fig. 3A, but the length of gap 34R becomes long, resulting in left-right asymmetry.

[0022] Fig. 4A is a diagram showing an example of a captured image when protective glass 27 is moderately dirty, and Fig. 4B is a diagram showing the state of protective glass 27 when protective glass 27 is moderately dirty. When protective glass 27 is moderately dirty as shown in Fig. 4B, the length of gap 34L is very long, and the length of gap 34R is also slightly longer than when there is no dirt, resulting in left-right asymmetrical appearance, as shown in Fig. 4A.

[0023] Fig. 5A is a diagram showing an example of a captured image when protective glass 27 is heavily soiled, and Fig. 5B is a diagram showing the state of protective glass 27 when protective glass 27 is heavily soiled. When protective glass 27 is heavily soiled as shown in Fig. 5B, both the length of gap 34L and the length of gap 34R are very long as shown in Fig. 5A.

[0024] 2A to 5A, the metal sheet W reflecting the light from the lighting device 11 is imaged, but it is possible to image the gap without installing the lighting device 11. For example, as shown in Fig. 6, if the brightness is increased by setting the camera 5 during imaging, it is possible to see that there is an area 61 corresponding to the gap around the emitted light 31. Therefore, when the lighting device 11 is not installed, the length of the gap can be measured using the area 61.

[0025] The reason why the gaps 34L and 34R are long or asymmetric in this way is believed to be that the focused diameter of the laser beam at the processing point becomes large or the shape of the laser beam becomes asymmetric due to contamination on the protective glass 27. Therefore, it is possible to determine whether the protective glass 27 is contaminated or not based on the gap formed between the synchrotron radiation 31 and the metal sheet W on the captured image. In particular, it is possible to determine whether the protective glass 27 is contaminated or not by measuring the length of the gap.

[0026] Therefore, the control unit 7 measures the length of the gap between the synchrotron radiation 31 and the metal plate W on the captured image, and determines that the protective glass 27 is dirty if the measured gap length is equal to or greater than the first threshold value. The gap length does not need to be measured on the left and right of the synchrotron radiation center 31A, and may be measured in other areas such as in front of the synchrotron radiation center 31A. Instead of the gap length, the area of ​​the region in which the gap is formed may be measured. Furthermore, the ratio of the lengths of the left and right gaps may be calculated, and if the calculated ratio of the lengths is outside a predetermined range, the lengths of the left and right gaps may be determined to be asymmetric, and the protective glass 27 may be determined to be dirty. For example, if the ratio of the lengths of the left and right gaps 34L and 34R is outside the range of 0.9 to 1.1, the lengths of the left and right gaps 34L and 34R are determined to be asymmetric, and the protective glass 27 is determined to be dirty.

[0027] The control unit 7 is configured by a computer having a memory, a processor such as a CPU (Central Processing Unit), and various interfaces. The memory and various interfaces are connected to the processor via a bus. The control unit 7 executes a process of detecting dirt on the protective glass 27 by executing a program stored in the memory by the processor. The control unit 7 may be provided in an NC (Numerical Control) device that controls the entire laser processing machine 1.

[0028] [Detection of dirt on protective glass] Next, a process for detecting dirt on a protective glass by the laser processing machine 1 according to this embodiment will be described. Fig. 7 is a flowchart showing the procedure of the process for detecting dirt on a protective glass. The process for detecting dirt on a protective glass starts when laser processing by the laser processing machine 1 is started.

[0029] 7, in step S101, the control unit 7 acquires an image captured by the camera 5. When a laser beam is emitted from the laser oscillator 9, the camera 5 captures an image of the radiant light emitted from the processing point of the metal sheet W. The captured image is output from the camera 5 and acquired by the control unit 7. The captured image may be temporarily stored in a memory (not shown) and then acquired by the control unit 7 from the memory.

[0030] In step S103, the control unit 7 measures the length of the gap between the synchrotron radiation and the metal sheet W on the captured image. A specific method of measuring the gap length will be described with reference to Figs. 8 and 9. Fig. 8 is a diagram for explaining the method of measuring the gap length when there is no dirt on the protective glass 27, and Fig. 9 is a diagram for explaining the method of measuring the gap length when there is dirt on the protective glass 27.

[0031] As shown in Fig. 8, the control unit 7 binarizes the acquired image 81 and converts it into a binarized image 82. Next, the control unit 7 performs a closing process on the binarized image 82. In the closing process, the white parts of the binarized image are enlarged to eliminate the black parts, and then the enlarged parts are returned to their original size. This makes it possible to clarify the white parts of the binarized image, such as the synchrotron radiation 31 and the metal sheet W.

[0032] The control unit 7 detects the portion of the synchrotron radiation 31 from the binarized image, and extracts the contour 83 of the synchrotron radiation 31. Next, the control unit 7 detects the portion of the metal sheet W from the binarized image, and measures the lengths of the gaps 34L, 34R between the synchrotron radiation 31 and the metal sheet W. In this manner, when there is no dirt on the protective glass 27, the lengths of the gaps 34L, 34R are approximately the same and short.

[0033] On the other hand, as shown in FIG. 9, when the protective glass 27 is heavily soiled and the lengths of the gaps 34L, 34R are measured in the same manner as in FIG. 8, the lengths of the gaps 34L, 34R are both larger than when there is no soiling.

[0034] When the lengths of the left and right gaps 34L and 34R are calculated in this manner, the control unit 7 may calculate the total length of the left and right gaps as the gap length, or may select the longer of the left and right gaps as the gap length. The control unit 7 may also calculate the ratio between the lengths of the left and right gaps.

[0035] In step S105, the control unit 7 determines whether the length of the gap measured in step S103 is equal to or greater than a first threshold, and if the length of the gap is equal to or greater than the first threshold, proceeds to step S107, and if the length of the gap is less than the first threshold, proceeds to step S115.

[0036] In step S107, the control unit 7 determines whether the gap length measured in step S103 is equal to or greater than the second threshold, and proceeds to step S109 if the gap length is equal to or greater than the second threshold, and proceeds to step S113 if the gap length is less than the second threshold. As shown in Fig. 10, the control unit 7 sets two thresholds, a first threshold and a second threshold, and determines whether to continue laser processing.

[0037] As shown in FIG. 10, the first threshold is a threshold for determining whether or not to reduce the moving speed of the laser beam. When the length of the gap is equal to or greater than the first threshold, the control unit 7 determines that the protective glass 27 is dirty and reduces the moving speed of the laser beam. By reducing the moving speed of the laser beam instead of stopping the processing in this way, processing defects such as rough cutting surfaces and dross are prevented. Therefore, the first threshold may be set to the length of the gap when processing defects start to occur. This prevents the number of times the protective glass 27 needs to be replaced more than necessary, and reduces the occurrence of processing defects.

[0038] The second threshold is set to a value larger than the first threshold, and is a threshold for determining whether or not to stop the laser processing. Therefore, the second threshold is set to a value at which the size of the product cut out from the sheet metal W becomes a predetermined allowable value based on the allowable error set by the user. If the length of the gap becomes large, the sheet metal W is cut more than normal, so the size of the product cut out from the sheet metal W becomes smaller as the length of the gap becomes large.

[0039] For example, images of the cut portion of the metal sheet W are shown in Figs. 11A and 11B. Fig. 11A is an example of an image of the cut portion of the metal sheet W when the protective glass 27 is not dirty, and Fig. 11B is an example of an image of the cut portion of the metal sheet W when the protective glass 27 is heavily dirty. As shown in Fig. 11A, when the protective glass 27 is not dirty, the width of the cut portion is 471 μm, whereas as shown in Fig. 11B, when the protective glass 27 is heavily dirty, the width of the cut portion is as large as 680 μm. Also, Fig. 11B shows that the area of ​​alteration on the surface of the cut portion of the metal sheet W is large.

[0040] When the protective glass 27 becomes dirty and the length of the gap increases, the width of the cut portion increases, and the size of the product cut out from the metal sheet W decreases. Therefore, if the length of the gap when the size of the product cut out from the metal sheet W becomes the allowable value is set to the second threshold value, processing can be stopped before the product becomes too small and exceeds the allowable error. If the protective glass 27 is replaced at this time, the number of times the protective glass 27 is replaced can be minimized.

[0041] In step S109, since the length of the gap is equal to or greater than the second threshold, the control unit 7 notifies the NC device to stop laser processing by the laser processing machine 1. In step S111, the control unit 7 outputs a protective glass contamination notification indicating that contamination requiring replacement has occurred on the protective glass 27, and notifies the user that laser processing has been stopped due to contamination on the protective glass 27. When the protective glass contamination notification is output, the protective glass contamination detection process according to this embodiment ends.

[0042] In step S113, since the length of the gap is equal to or greater than the first threshold, the control unit 7 reduces the moving speed of the laser beam to continue processing. At this time, the moving speed may be reduced to a preset speed, or may be reduced to a lower speed as the length of the gap increases.

[0043] In step S115, the control unit 7 determines whether or not laser processing by the laser processing machine 1 has been completed. If not, the process returns to step S101; if completed, the process for detecting dirt on the protective glass in this embodiment is terminated.

[0044] [Effects of the embodiment] As described above in detail, the laser processing machine 1 according to this embodiment judges whether or not the protective glass 27 is dirty based on the gap between the radiant light on the captured image and the metal sheet W. This makes it possible to detect dirt on the protective glass 27 while monitoring the processing state of the metal sheet W, and therefore makes it possible to detect dirt on the protective glass 27 in-line (during processing).

[0045] Furthermore, the laser processing machine 1 according to this embodiment measures the length of the gap on the captured image, and determines that the protective glass 27 is dirty if the measured gap length is equal to or greater than a first threshold value. This makes it possible to specifically measure the dirt on the protective glass 27 by the gap length, and therefore makes it possible to accurately determine whether or not the protective glass 27 is dirty.

[0046] Furthermore, the laser processing machine 1 according to this embodiment reduces the moving speed of the laser beam when the length of the gap is equal to or greater than the first threshold value, which prevents the protective glass 27 from being replaced more frequently than necessary and reduces the occurrence of processing defects such as rough cut surfaces and dross.

[0047] Moreover, the laser processing machine 1 according to this embodiment stops the laser processing when the length of the gap is equal to or greater than a second threshold value that is greater than the first threshold value. This makes it possible to stop the laser processing and replace the protective glass 27 when the dirt on the protective glass 27 becomes large.

[0048] Furthermore, the laser processing machine 1 according to this embodiment sets the gap length when the size of the product cut out from the metal sheet W becomes the allowable value to the second threshold value. This makes it possible to stop processing before the product exceeds the allowable error, thereby minimizing the number of times the protective glass 27 needs to be replaced.

[0049] As described above, the embodiment of the present invention has been described, but the description and drawings forming a part of this disclosure should not be understood as limiting this invention. From this disclosure, various alternative embodiments, examples and operating techniques will become apparent to those skilled in the art. [Explanation of symbols]

[0050] 1 Laser processing machine 3 Processing head 5. Camera 7 Control section 9 Laser Oscillator 11 Lighting equipment 13 Bandpass Filter 15 Imaging Lens 17, 19 Collimating lens 21 Beam splitter 23 Bend Mirror 25 Focusing Lens 27 Protective Glass 31 Synchrotron Radiation 31A Synchrotron radiation center 33 Calf 34L, 34R Gap 61 areas 81 images 82 Binarized Images 83 Contour

Claims

1. a camera that captures an image of radiation light emitted from a processing point of the metal sheet when the metal sheet is cut by irradiating the metal sheet with a laser beam from a processing head; a control unit that detects dirt on a protective glass provided on the processing head based on the radiation light captured by the camera, The control unit determines whether the protective glass is dirty based on a gap between the emitted light and the metal plate on a captured image. Laser processing machine.

2. The control unit measures a length of the gap on the captured image, and determines that the protective glass is dirty when the measured length of the gap is equal to or greater than a first threshold value.

2. The laser processing machine according to claim 1.

3. The control unit reduces a moving speed of the laser beam when the length of the gap is equal to or greater than the first threshold value.

3. The laser processing machine according to claim 2.

4. The control unit stops laser processing when the length of the gap is equal to or greater than a second threshold value that is greater than the first threshold value.

4. The laser processing machine according to claim 2 or 3.

5. When a laser beam is irradiated from a processing head of a laser processing machine to cut a metal sheet, a camera captures an image of the radiation emitted from a processing point of the metal sheet; Whether or not a protective glass provided on the processing head is dirty is determined based on a gap between the emitted light and the metal plate on the captured image. A method for detecting dirt on protective glass.

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