JP7296769B2 - Spatter detection device, laser processing device, and method for detecting spatter - Google Patents

Description

The present invention relates to a spatter detection device, a laser processing device, and a spatter detection method.

As an industrial processing tool, a laser processing apparatus is widely used. In general, laser processing generates spatter. A spatter is a scattering fine particle of molten metal. If the spatter adheres to the work (workpiece), it may lead to quality deterioration of the work. Further, when the spatter adheres to the optical system of the laser processing apparatus, the adhered spatter absorbs the laser beam, which raises the temperature of the adhering portion, which may cause thermal distortion in the optical system. If thermal strain occurs in the optical system, there is a risk that the focusing of laser light will be hindered or the optical system will be damaged.

If the occurrence of spatter can be detected in-line in parallel with laser processing, defective products to which spatter adheres can be immediately removed. Also, the amount of spatters generated varies depending on the processing conditions and the state of the workpiece. Therefore, by detecting the generation of spatter in-line and immediately identifying the cause of the generation, it is possible to reduce the amount of subsequent generation of spatter. As a result, productivity can be improved, and damage to the laser processing apparatus can be suppressed.

Regarding the detection of spatter, for example, Patent Document 1 describes a collection hole for collecting spatter generated from the periphery of the weld during spot welding, a spatter collector connected to the collection hole, and a spatter collector. A spatter detection apparatus is disclosed that includes a spatter amount meter for measuring the amount of spatter collected and an electronic computer for processing the measured spatter amount data.

JP 2013-151028 A

The spatter detector described above directly collects spatter generated during spot welding of steel plates and measures the amount of spatter. Therefore, there is a problem that the detection of spatter is complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique for detecting spatter more easily.

In order to solve the above problems, one aspect of the present invention is a spatter detection device. The spatter detection device is a spatter detection device that detects spatter generated in laser processing of a work, and includes a photodetector that detects light emitted by the spatter scattered from a laser beam irradiation point on the work.

Another aspect of the present invention is a laser processing apparatus. The laser processing apparatus includes an emission head that emits laser light toward a work, and the spatter detection device of the aspect described above.

Another aspect of the present invention is a spatter detection method. The detection method is a method of detecting spatter generated in laser processing of a work, and detects light emitted by spatter scattered from a laser beam irradiation point on the work.

Any combination of the above constituent elements, and conversion of expressions of the present invention between methods, devices, systems, etc. are also effective as aspects of the present invention.

According to the present invention, spatter can be detected more easily.

1 is a schematic diagram of a laser processing apparatus according to an embodiment; FIG. FIG. 2A is a perspective view schematically showing the detection area of the photodetector. FIG. 2B is a side view schematically showing the detection area of the photodetector. FIG. 4 is a schematic diagram for explaining determination of occurrence of spatter by a spatter determination unit;

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on preferred embodiments with reference to the drawings. The embodiments are illustrative rather than limiting the invention, and not all features and combinations thereof described in the embodiments are necessarily essential to the invention. The same or equivalent constituent elements, members, and processes shown in each drawing are denoted by the same reference numerals, and duplication of description will be omitted as appropriate. In addition, the scale and shape of each part shown in each drawing are set for convenience in order to facilitate the explanation, and should not be construed as limiting unless otherwise mentioned. In addition, when terms such as "first" and "second" are used in this specification or claims, unless otherwise specified, these terms do not represent any order or degree of importance, and only one configuration. and other configurations. Also, in each drawing, some of the members that are not important for explaining the embodiments are omitted.

FIG. 1 is a schematic diagram of a laser processing apparatus according to an embodiment. Only one photodetector 20 is shown in FIG. Moreover, in FIG. 1, some of the constituent elements of the spatter detection device 6 are drawn as functional blocks. These functional blocks are implemented by elements and circuits such as a CPU and memory of a computer as hardware configurations, and are implemented by computer programs and the like as software configurations. It should be understood by those skilled in the art that these functional blocks can be realized in various forms by combining hardware and software.

A laser processing apparatus 1 is an apparatus for irradiating a workpiece W, which is a metal workpiece, with a laser beam L to process the workpiece W. The laser processing apparatus 1 includes a transmission fiber 2, an emission head 4, a spatter detection device 6, Prepare. Processing of the work W in the present embodiment is welding of the work W. As shown in FIG. The processing of the workpiece W may be drilling, cutting, surface treatment, or the like.

The transmission fiber 2 connects an external laser oscillator (not shown) and the emission head 4 to transmit laser light generated by the laser oscillator to the emission head 4 . A known laser oscillator such as a YAG laser oscillator, a _CO2 laser oscillator, an excimer laser oscillator, or the like can be used as the laser oscillator. In the laser processing apparatus 1 of the present embodiment, an infrared laser beam in a wavelength range of about 1000 nm is used as an example.

The emission head 4 is a mechanism that emits the laser beam L toward the work W, and has a housing 8 , a reflecting mirror 10 , a first lens 12 , a second lens 14 and a protective glass 16 . The housing 8 has a bottomed cylindrical shape with an opening 8a on one end side, and is arranged so that the opening 8a faces the work W side. Inside the housing 8, a reflecting mirror 10, a first lens 12 and a second lens 14 are accommodated. Reflecting mirror 10 , first lens 12 and second lens 14 are supported by housing 8 . A protective glass 16 is attached to the opening 8a.

A transmission fiber 2 is connected to the side surface of the housing 8 . The laser light L transmitted from the transmission fiber 2 to the output head 4 is applied to the reflecting mirror 10 . The reflecting mirror 10 is a member that reflects the light of the output wavelength of the laser oscillator. The reflecting mirror 10 is positioned so as to reflect the laser light L emitted from the transmission fiber 2 toward the opening 8a. A first lens 12 and a second lens 14 are arranged between the reflecting mirror 10 and the protective glass 16 . The first lens 12 is arranged closer to the reflecting mirror 10 than the second lens 14 , and the second lens 14 is arranged closer to the protective glass 16 than the first lens 12 .

The laser beam L reflected by the reflecting mirror 10 enters the first lens 12 . The first lens 12 is a collimating lens, converts the incident laser light L into parallel light, and emits the parallel light toward the second lens 14 . The second lens 14 is a focus lens that collects the incident laser beam L and emits it toward the workpiece W. As shown in FIG. The laser beam L emitted from the second lens 14 passes through the protective glass 16 and irradiates the workpiece W. As shown in FIG.

By irradiating the surface of the work W with the laser light L, the metal forming the work W at the irradiation point P of the laser light L melts. At least one of the work W and the ejection head 4 can be moved by a moving mechanism (not shown). The irradiation point P is moved by relatively displacing the workpiece W and the ejection head 4 by driving the moving mechanism. As a result, the metal melted at the irradiation point P before movement is cooled and solidified. As a result, the work W is welded.

The spatter detection device 6 is a device for detecting spatter S generated during laser processing of the work W, and includes a photodetector 20 . Moreover, the spatter detection device 6 of the present embodiment has a spatter determination section 24 .

The photodetector 20 can be composed of a known photosensor such as a solid-state imaging device such as a CCD image sensor or a CMOS image sensor, or a photodiode. The photodetector 20 detects the light emitted by the spatter S scattering from the irradiation point P of the laser beam L on the workpiece W (hereinafter also referred to as the spatter light S1 as appropriate). The photodetector 20 of the present embodiment is provided around the emission head 4 so that the irradiation point P is out of the detection area 20a.

FIG. 2A is a perspective view schematically showing the detection area 20a of the photodetector 20. FIG. FIG. 2B is a side view schematically showing the detection area 20a of the photodetector 20. FIG. In this embodiment, four photodetectors 20 are provided so as to surround the outer periphery of the emission head 4 . Moreover, the four photodetectors 20 are arranged so that the irradiation point P is not included in each detection area 20a, and the periphery of the irradiation point P is surrounded by the four detection areas 20a. That is, the irradiation point P is positioned outside the detection range of each photodetector 20 . The number of photodetectors 20 is not particularly limited, and may be a plurality other than four, or may be only one.

The range of the detection area 20a of the photodetector 20 is adjusted by an optical element (not shown) such as a lens. As a result, the irradiation point P is removed from the detection area 20a. For example, the photodetector 20 is provided with a cylindrical lens on the light receiving surface, and the detection area 20a is adjusted to be long in one direction. The four photodetectors 20 are then positioned relative to each other such that each detection area 20a constitutes a respective piece of a square.

In the welding of the work W, the plasma light generated in the welding process and the laser light L reflected by the work W are irradiated from the irradiation point P to the surroundings. These lights are much higher in intensity than the sputtered light S1 emitted by the sputters S. Therefore, when the photodetector 20 receives these lights, detection of the sputtered light S1 is hindered. On the other hand, by providing the photodetector 20 so that the irradiation point P is not included in the detection area 20a, it is possible to prevent the plasma light and the reflected laser beam L that cause disturbance from directly entering the photodetector 20. can be suppressed.

Further, the photodetector 20 of the present embodiment has sensitivity in the infrared wavelength range, and substantially I am insensitive. The photodetector 20 as an example is substantially insensitive to both the visible light wavelength range and the laser light L wavelength range. That is, the photodetector 20 has higher sensitivity to the infrared wavelength range than to at least one of the visible light wavelength range and the laser light L wavelength range. The infrared wavelength range is, for example, 760 to 1000 nm, and the visible light wavelength range is, for example, 380 to 760 nm. The plasma light contains a large amount of visible light, and the sputter light S1 contains a large amount of infrared light. Therefore, by setting the light-receiving sensitivity (imaging sensitivity) of the photodetector 20 so as to be substantially insensitive to the wavelength region of visible light, the influence of the plasma light, which is a disturbance, on the photodetector 20 can be reduced. can be reduced, and the detection sensitivity of the sputtered light S1 in the photodetector 20 can be enhanced. In addition, by setting the light receiving sensitivity of the photodetector 20 so as to be substantially insensitive to the wavelength range of the laser light L, the influence of the laser light L as a disturbance on the photodetector 20 can be reduced. , the detection sensitivity of the sputtered light S1 in the photodetector 20 can be increased.

The above light sensitivity can be realized by providing the photodetector 20 with a band-pass filter that passes infrared rays and cuts visible light, for example. The phrase "substantially insensitive" means that a photodetector sensitive to visible light is allowed to the extent that detection of the spatters S by the spatter detector 6 is not hindered. The extent to which the detection of the spatters S is not disturbed can be appropriately set based on the designer's empirical knowledge or the designer's experiments, simulations, or the like.

The photodetector 20 outputs a signal corresponding to the amount of received light to the spatter determination section 24 . The output signal of the photodetector 20 is, for example, a voltage having a magnitude corresponding to the received light intensity.

The spatter determination unit 24 determines the occurrence of the spatter S for each workpiece W based on the output signal from the photodetector 20, and displays the result on a display device, stores it in a storage device, or Send to an external device. FIG. 3 is a schematic diagram for explaining determination of generation of spatter S by the spatter determination unit 24. As shown in FIG. The spatter determination unit 24 holds in advance a predetermined threshold value T that serves as a reference for determination of occurrence of spatter S. The threshold value T can be appropriately set based on the designer's empirical knowledge or the designer's experiment, simulation, or the like. The threshold value T is the threshold value of the intensity of light received by the photodetector 20. For convenience of explanation, the intensity of the output signal corresponding to the threshold value T is indicated as T in FIG. .

The spatter determination unit 24 determines that the spatter S is generated when the photodetector 20 detects light having an intensity equal to or higher than a predetermined threshold value T. FIG. That is, when the intensity of the output signal from the photodetector 20 is equal to or greater than the threshold value T, the spatter determination unit 24 determines that the spatter S has occurred. The spatter determination unit 24 displays, for example, the occurrence of the spatter S on the display device. Thereby, the user of the laser processing apparatus 1 can easily grasp that the spatter S has occurred.

As described above, the spatter detection device 6 according to the present embodiment is a device for detecting the spatter S generated in the laser processing of the work W, and the spatter S scattered from the irradiation point P of the laser light L on the work W. is provided with a photodetector 20 for detecting the light of The laser processing apparatus 1 of the present embodiment also includes an emission head 4 that emits the laser beam L toward the work W, and a spatter detection device 6 .

The spatter detection device 6 detects the occurrence of the spatter S based on the change in the amount of light received by the photodetector 20 when the spatter S passes through the detection region 20a. For this reason, according to the present embodiment, the spatter S can be detected more easily than the conventional spatter detection apparatus that directly collects the spatter S with the spatter collector and measures the amount of spatter. can be done.

As a conventional method for judging spatters, an inspector visually inspects the generation of spatters S off-line or using an inspection device, or records an image during laser processing and performs image processing on the image. There has been a method of detecting the spatter S by On the other hand, the spatter detection device 6 of the present embodiment can detect the generation of the spatter S in-line in parallel with the laser processing. Therefore, the occurrence of spatters S can be detected early. In addition, if the spatter detection device 6 of the present embodiment is used, there is no need to secure expensive equipment for photographing or space for photographing, so the cost and space required for detecting the spatters S can be reduced. .

Moreover, since the spatter detection device 6 of the present embodiment has a simple configuration and a small size, it can be easily mounted on the emission head 4 . Accordingly, it is possible to suppress an increase in the size of the laser processing apparatus 1 due to the provision of the spatter detection device 6 in the laser processing apparatus 1 . That is, according to the present embodiment, it is possible to provide a compact laser processing apparatus 1 having a spatter detection function. In addition, since the spatter detection device 6 is small, it can also be preferably used for detection of spatter S in laser processing such as seam welding in which welding points are continuous. In other words, according to the present embodiment, it is possible to provide a highly versatile spatter detection device 6 .

Further, the photodetector 20 of the present embodiment is provided so that the irradiation point P is outside the detection area 20a. As a result, it is possible to suppress the direct incidence of the plasma light and the reflected laser light L that cause disturbance to the photodetector 20 . On the other hand, the spatter S scatters from the irradiation point P and enters the detection area 20a. Therefore, the sputtered light S1 directly enters the photodetector 20 . Therefore, the ratio of the sputtered light S1 to the total light received by the photodetector 20 can be increased. As a result, it is possible to improve the detection accuracy of the sputtered light S1.

Further, the photodetector 20 of the present embodiment has sensitivity in the infrared wavelength range, and is substantially insensitive to at least one of the wavelength range of visible light and the wavelength range of the laser light L. be. As a result, it is possible to suppress the plasma light and the laser light L that cause disturbance from entering the light receiving surface of the photodetector 20 . On the other hand, the sputtered light S1 can enter the light receiving surface of the photodetector 20 . Therefore, the ratio of the sputtered light S1 to the total light received by the photodetector 20 can be further increased. As a result, it is possible to improve the detection accuracy of the sputtered light S1.

The spatter detector 6 of the present embodiment also has a spatter determination unit 24 that determines that the spatter S has occurred when the photodetector 20 detects light having an intensity equal to or higher than a predetermined threshold value T. FIG. Thereby, the user of the laser processing apparatus 1 can easily grasp the generation of the spatter S inline.

Further, the present embodiment also includes provision of a method for detecting spatters S. FIG. That is, another aspect of the present embodiment is a method for detecting spatter S generated in laser processing of a work W, in which light emitted by the spatter S scattered from the irradiation point P of the laser light L on the work W is detected. detection method.

The embodiments of the present invention have been described in detail above. The above-described embodiments merely show specific examples for carrying out the present invention. The contents of the embodiments do not limit the technical scope of the present invention, and many design changes such as changes, additions, and deletions of constituent elements are possible without departing from the spirit of the invention defined in the claims. is possible. In the above-described embodiments, the content that allows such design changes is emphasized by adding notations such as "in this embodiment" and "in this embodiment". Design changes are allowed even if there is no content. Any combination of components included in the embodiments is also effective as an aspect of the present invention. A new embodiment obtained by design change or combination of constituent elements has the effects of the combined constituent elements and modifications.

1 laser processing device, 4 emission head, 6 spatter detection device, 20 photodetector, 20a detection area, 24 spatter determination section, L laser beam, P irradiation point, S spatter, W work.

Claims (6)

A spatter detection device for detecting spatter generated in laser processing of a work,
A photodetector for detecting light emitted by spatter scattered from the irradiation point of the laser light on the work ,
A spatter detection apparatus, wherein the photodetector has a cylindrical lens and is provided so that the irradiation point is out of a detection area . The sputter detection device includes a plurality of the photodetectors,
2. The spatter detection apparatus according to claim 1, wherein the plurality of photodetectors are arranged so as to surround the outer periphery of the irradiation point by combining respective detection areas . 3. The photodetector according to claim 1 or 2, wherein the photodetector is sensitive to an infrared wavelength region and is substantially insensitive to at least one of the wavelength region of visible light and the wavelength region of the laser light. The sputter detector as described. 4. The spatter detection apparatus according to claim 1, further comprising a spatter determination unit that determines that the spatter has occurred when light having an intensity equal to or higher than a predetermined threshold value is detected by the photodetector. . an emission head for emitting a laser beam toward a work;
A sputter detection device according to any one of claims 1 to 4;
A laser processing device comprising: A method for detecting spatter generated in laser processing of a work, comprising:
A detection method comprising detecting light emitted by spatter scattered from a laser beam irradiation point on the workpiece , using a photodetector having a cylindrical lens and provided so that the irradiation point is out of a detection area. .

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