JP2005334957A - Weld zone visualizing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a weld zone visualizing apparatus capable of directly observing the entire weld zone and aquiring information of an uneven shape by a single camera. <P>SOLUTION: A wavelength separation mirror 30 to perform the wavelength separation of short pulse laser beams 3, 31 is provided on the emission side of a short pulse laser beam source 2 to simultaneously output the short pulse laser beams 3, 31 of the second harmonic and the fundamental harmonic of Nd-YAG laser, and an optical system 8a for the high intensity illumination to irradiate the second harmonic short pulse laser beams 3 to a weld zone for the high brightness illumination and an optical system 33 for the measurement of optical cutting to project the fundamental short pulse laser beams 31 to the weld zone as fan beams 32 are provided. A camera 4 to pick up an image of the weld zone and a timing device 6 to synchronize the irradiation timing of the short pulse laser beam source 2 with the opening/closing operation of a high-speed shutter 5 are provided. The image of the weld zone when it is illuminated more intensely than the light emission intensity of a molten pool 1 with the second harmonic short pulse laser beams 3 and the optical cutting image 39 on the surface of a base material 12 with fan beams 32 of the fundamental harmonic short pulse laser beams 31 are simultaneously picked up by the camera 4. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a weld visualization device used for observing a weld when performing welding such as laser welding, plasma welding, or arc welding.

  When welding is performed, observing the weld pool including the generated weld pool and its peripheral part, for example, the state of the groove located in front of the welding direction and the state of the bead formed after welding, etc. It is important for management and stabilization.

  However, light such as laser, plasma, and arc scattered light used for welding is emitted intensely from the weld during welding. In particular, laser welding and plasma welding scatter laser and plasma rather than weld pool light emission. Because the light is stronger, for example, even if you try to shoot with a camera equipped with an optical neutral density filter, the molten pool part will cause halation due to excessive light quantity, so it is not possible to observe the molten pool It is extremely difficult.

  For this reason, as a technique for monitoring a welded part in laser welding, a technique of directly observing with a camera using a strong (high brightness) illumination light source has been proposed. As an apparatus used for such a technique, the present applicant has proposed a weld visualizing apparatus as shown in FIG.

  This comprises a short pulse laser light source 2 for irradiating the molten pool 1 by laser welding with a short pulse laser beam 3 having a higher brightness than the molten pool 1 and a high-speed shutter 5 for photographing the vicinity of the molten pool 1. A camera 4; and a timing device 6 that synchronizes the irradiation timing of the short pulse laser light 3 from the short pulse laser light source 2 with the opening and closing of the high-speed shutter 5 of the camera 4, and the wavelength of the short pulse laser light 3 And a filter 7 for reducing the laser scattered light by cutting the required wavelength region in the scattered light of the continuous laser light used for laser welding. ing.

  Reference numeral 8 denotes an optical system for high-intensity illumination comprising a mirror 9 and a lens 10 and the like, and a short pulse laser beam 3 emitted from the short pulse laser light source 2 is welded through the mirror 9 and the lens 10; In other words, the molten pool 1 and its peripheral part can be irradiated with a required spread. Reference numeral 11 denotes a laser welding torch, 12 denotes a base material to be welded, and 13 denotes a monitor for displaying an image of the camera 4.

  Thereby, according to the said weld part visualization apparatus, toward the molten pool 1 formed in the base material 12 with the laser welding torch 11, the short pulse laser beam whose brightness is higher than the molten pool 1 rather than the said short pulse laser light source 2. By irradiating 3 for illumination, the molten pool 1 and its peripheral part are given emission intensity higher than the laser scattered light, and at the same time, by the high-speed shutter 5 synchronized with the irradiation timing of the filter 7 and the short pulse laser light source 2. On the monitor 13, the light from the molten pool 1 that has been illuminated with high brightness is incident on the camera 4, while the harmful light such as laser scattered light other than that is almost cut off to greatly reduce the amount of incident light. It becomes possible to perform visual observation of the weld pool 1 and its peripheral part in the welded part without causing halation (see, for example, Patent Document 1).

  Incidentally, an Nd-YAG laser is used as the short pulse laser light source 2 in the weld visualization device. The fundamental wave of the Nd-YAG laser is light in the infrared region having a wavelength of 1064 nm. However, the CCD used in the camera 4 can obtain only about 10% of the sensitivity to visible light because of its optical characteristics. On the other hand, the second harmonic wave having a wavelength of 532 nm obtained by converting the wavelength of the fundamental wave (light having a wavelength of 1064 nm) of the Nd-YAG laser has a conversion efficiency of only about 50% from the fundamental wave. However, since it is visible light (green light), the detection sensitivity of the CCD can be obtained about 10 times that of the fundamental wave. Therefore, conventionally, in order to increase the detection efficiency in the CCD of the camera 4, the short pulse laser beam 3 used for high-intensity illumination of the welded portion is a wavelength oscillated as an Nd-YAG laser. A second harmonic wave having a wavelength of 532 nm obtained by converting the wavelength of the fundamental wave of 1064 nm in the short pulse laser light source 2 is used. As described above, the wavelength conversion from the fundamental wave to the second harmonic of the Nd-YAG laser has a conversion efficiency of only about 50%, so that a short pulse emitted from the short pulse laser light source 2 is used. The laser beam 3 includes a fundamental wave that remains without being wavelength-converted together with the second harmonic.

  For this reason, in the melting part visualizing apparatus, a short pulse laser beam emitted from the short pulse laser light source 2 is normally used with a mirror 9 provided immediately after the emission side of the short pulse laser light source 2 as a wavelength separation type mirror. 3 is applied to the wavelength separation type mirror 9 to separate the fundamental wave from the second harmonic, and then the short pulse laser beam 3 consisting only of the second harmonic from which the fundamental wave is separated and removed is Irradiation is made toward the molten pool 1 and its peripheral part through the optical system 8 for high brightness illumination.

  The fundamental wave separated from the second harmonic in the wavelength separating mirror 9 is dissipated in energy by, for example, irradiating it toward a damper plate (not shown) made of polytetrafluoroethylene. It is.

  Another method that has been proposed in the past for observing the periphery of a welded portion is a light cutting method in which shape measurement is performed by projecting a planar light beam onto the welded portion to obtain a light cut image. . As an apparatus employing such a light cutting method, for example, an arc welding monitoring apparatus as shown in FIG. 4 has been conventionally proposed.

  This is because, in order to perform shape measurement by the optical cutting method, a predetermined welding position separated by a required dimension in front of the welding direction from a welding position at a certain point in the butt welding portion between the workpieces 14 such as steel plates. From the slit light projector 16 that projects a slit-shaped light beam (slit light) 17 onto the groove portion 15, the cross-sectional shape measurement camera 18 that captures the position where the slit light 17 is projected, and the image of the camera 18, The image processing apparatus 20 extracts a bright line generated on the surface of the workpiece 14 by the projection of the slit light 16, that is, a cross-sectional profile (light cut image) 19 as information on the cross-sectional shape of the welded portion. Further, the arc welding monitoring device is provided with an arc camera 24 for photographing a welding arc 22 generated by the welding torch 21 and a pool (a molten pool) 23 of the generated weld metal, and is obtained by the image processing device 20. 5 (a), a light cut image 19 of the material to be welded 14 and the groove portion 15, and an image of the welding arc 22 and the molten pool 23 as shown in FIG. Are combined with each other and displayed on the monitor 25 as a composite image as shown in FIG.

  In addition, 27 is a camera controller provided for each of the cameras 18 and 24, 28 is a memory for temporarily storing information on the cross-sectional shape of the welded portion extracted as the light section image 19 by the image processing device 20, and 29 is a timing controller. The timing controller 29 shifts the projection position of the slit light 17 set in front of the required dimension in the welding progress direction from the welding position at a certain point of time and the welding position photographed by the arc camera 24. In consideration, the light section image 19 captured in advance by the cross-sectional shape measurement camera 18 is synthesized in accordance with the display timing of the arc image of the welded portion captured by the arc camera 24.

  Thereby, in the said arc welding monitoring apparatus, the cross-sectional light section image 19 of the groove part 15 currently formed between the welding arc 22 and the molten pool 23 in the welding part, and the to-be-welded materials 14 is simultaneously 1 Observation is possible on two monitors 25 (see, for example, Patent Document 2).

  In addition, instead of the slit light 17, a spot-like laser beam is used as a planar light beam projected onto the measurement object in the light cutting method, or a fan made by expanding the laser light through a lens. It has also been considered to use a beam (laser stripe).

JP 11-179578 A Japanese Patent Laid-Open No. 10-6006

  However, the weld visualization device shown in FIG. 3 is effective because it can observe the entire weld pool in the weld pool 1 and its surroundings. However, the actual condition is that it is difficult to actually measure the concave / convex shape, for example, the concave / convex shape such as the deviation of the groove in the butt weld.

  On the other hand, the light cutting method is suitable for measurement of the uneven shape on the surface of the measurement object, but it is difficult to simultaneously acquire information on the entire welded part, for example, information on the molten pool and its peripheral part.

  In the arc welding monitoring apparatus as shown in FIG. 4 above, an image of observation data of the welding arc 22 and the molten pool 23 by the arc camera 24 and a light section image of the groove portion 15 obtained by the cross-sectional shape measurement camera 18 are obtained. The visual information of the light section image 19 formed by the slit light 17 is prevented from being canceled by the light of the welding arc 22. Therefore, in addition to the arc camera 24 for photographing the welding arc 22, a cross-sectional shape measurement camera 18 for obtaining the light section image 19 must be provided, and the cost increases because two cameras are installed. There is a problem.

  Furthermore, in order to prevent the visual information of the light-cut image 19 from being canceled out by the light of the welding arc 22, the projection position of the slit light 17 is a position away from the welding arc 22 by a required dimension forward in the welding direction. Must be set to For this reason, since the optical cutting image 19 and the observation data of the welding arc 22 and the weld pool 23 are shifted in time, there is also a problem that information on the uneven shape of the groove portion 15 immediately before welding cannot be obtained. .

  Further, what is described in Patent Document 2 is an apparatus for observing a welded portion in arc welding, and as described above, a laser that generates a brighter laser or plasma scattered light than a molten pool. In welding and plasma welding, since it is difficult to photograph the molten pool itself with a camera, it cannot be directly applied to laser welding or plasma welding.

  Therefore, the present inventors have further expanded and developed a conventional weld visualization device that directly observes with a camera using a powerful illumination light source with a short pulse laser beam, and under high-intensity illumination with a short pulse laser light source. The present invention has been made as a result of repeated efforts and research to simultaneously acquire information on the concavo-convex shape of a welded portion using a light section image while photographing the welded portion.

  Therefore, the purpose of the present invention is to simultaneously observe the entire welded portion at the time of various welding such as laser welding, plasma welding, arc welding, etc. by one camera without causing a significant increase in cost. It is an object of the present invention to provide a weld visualization device that can also acquire information on the uneven shape of a weld by a light cutting measurement technique.

  In order to solve the above-mentioned problem, the present invention corresponds to the invention according to claim 1, and corresponds to the invention for irradiating the welded portion with a short pulse laser beam having a brightness higher than that of the light emitted from the welded portion. An optical system for brightness illumination and a short pulse of the optical system for high brightness illumination in the form of a fan beam having a higher brightness than the light emitted from the welded portion by a short pulse laser beam having a wavelength different from that of the optical system for high brightness illumination An optical system for optical cutting measurement that irradiates the welded portion at a timing synchronized with the laser beam, and a camera having a high-speed shutter for photographing the welded portion, and a short pulse laser from each of the optical systems. It is configured to include a timing device that synchronizes the light irradiation timing with the opening and closing of the high-speed shutter of the camera.

  Further, in correspondence with the invention according to claim 2, the short pulse laser light source that simultaneously outputs two pulsed short pulse laser beams having different wavelengths with higher brightness than the light emitted from the welded portion is provided on the emission side. Provided with a wavelength separation part for separating the short pulse laser light emitted from the pulse laser light source for each wavelength, and irradiating the welding part with the short pulse laser light of one wavelength separated by the wavelength separation part An optical system for high-intensity illumination for irradiating for use, and an optical system for optical cutting measurement that irradiates the weld with a short pulse laser beam of the other wavelength in the form of a fan beam, and further images the weld And a timing device for synchronizing the irradiation timing of the short pulse laser light from the short pulse laser light source with the opening and closing of the high speed shutter of the camera. To.

  Furthermore, the short pulse laser light source in the invention according to claim 2 has a function of simultaneously emitting two wavelengths of a fundamental wave generated by laser oscillation and each harmonic wave obtained by wavelength conversion of the fundamental wave. .

  The short pulse laser light source according to the third aspect of the present invention has a configuration in which the fundamental wave of the Nd-YAG laser is internally wavelength-converted with a required conversion efficiency, and the fundamental wave and the second harmonic are emitted simultaneously.

  The optical cutting measurement optical system according to the invention according to claim 2, 3 or 4 has a function of projecting, as a plurality of fan beams, a short pulse laser beam incident from the wavelength separation unit to a plurality of locations in the welded portion. To do.

The weld visualization device according to the present invention exhibits the following excellent effects.
(1) A high-brightness illumination optical system for irradiating the welded part with a short pulse laser beam having a higher brightness than the light emitted from the welded part, and a short wavelength different from that of the high-brightness illumination optical system An optical system for optical cutting measurement that irradiates the welded portion with a pulse laser beam in the form of a fan beam that is brighter than the light emitted from the welded portion and is synchronized with the short pulse laser light of the optical system for high brightness illumination. And a camera having a high-speed shutter for photographing the welded portion, and a timing device for synchronizing the irradiation timing of the short pulse laser light from each optical system with the opening and closing of the high-speed shutter of the camera. Therefore, it is possible to illuminate the welded portion with a brightness higher than the light emission intensity of the welded portion by using short pulse laser beams having two different wavelengths, and at the same time, a light cut image is formed on the welded portion. The effect of harmful light such as scattered light generated from the weld by a camera equipped with a high-speed shutter can be used to display the image of the entire weld when it is illuminated with high brightness and the light cut image formed simultaneously. It is possible to shoot in a state where the image is suppressed. Therefore, direct observation of the welded portion and uneven shape information based on the light cut image can be obtained simultaneously. (2) As described above, direct observation of the welded portion and information acquisition of the concavo-convex shape can be realized with a structure including a single camera, so that the cost required for the apparatus can be suppressed.
(3) A short pulse laser emitted from the short pulse laser light source on the emission side of the short pulse laser light source that simultaneously outputs two different wavelength short pulse laser lights with higher brightness than the light emitted from the weld. For high-luminance illumination for providing a wavelength separation unit for separating light for each wavelength and irradiating the welded part with short-pulse laser light having one wavelength that is wavelength-separated by the wavelength separation unit. A camera comprising an optical system and an optical system for optical cutting measurement that irradiates a welded portion with a short pulse laser beam of the other wavelength in the form of a fan beam, and further includes a high-speed shutter for photographing the welded portion And a timing device that synchronizes the irradiation timing of the short pulse laser beam from the short pulse laser light source with the opening and closing of the high-speed shutter of the camera. And (2) can be obtained, and furthermore, high-intensity illumination of the welded portion and light in the welded portion can be obtained by using two short-pulse laser beams having different wavelengths output from the same short-pulse laser light source. Since a cut image can be formed, only one short pulse laser light source is required. Therefore, a timing device that synchronizes the irradiation timing of the short pulse laser light from the short pulse laser light source with the opening and closing of the high-speed shutter of the camera. Therefore, the cost required for the apparatus can be further suppressed.
(4) Further, the short pulse laser light source is configured to have a function of simultaneously emitting two wavelengths of a fundamental wave generated by laser oscillation and each harmonic wave obtained by wavelength conversion of the fundamental wave. It is possible to easily obtain a short pulse laser light source that outputs short pulse laser beams having different wavelengths.
(5) Further, the short pulse laser light source has a configuration in which the fundamental wave of the Nd-YAG laser is internally wavelength-converted with a required conversion efficiency, and the fundamental wave and the second harmonic are emitted simultaneously. A short pulse laser beam by the second harmonic of the Nd-YAG laser in the visible light region having a wavelength of 532 nm can be used as the luminance illumination, and a light cut image by a fundamental wave of the Nd-YAG laser having a wavelength of 1064 nm in the infrared region. Therefore, an image suitable for photographing with a CCD camera can be obtained.
(6) The optical section measuring optical system is configured to have a function of projecting a short pulse laser beam incident from the wavelength separation unit as a plurality of fan beams to a plurality of locations in the welded portion, thereby providing a plurality of locations in the welded portion. It is possible to obtain information on the uneven shape at the same time.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  1 (a) and 1 (b) show an embodiment of a welded portion visualization device of the present invention, which has the following configuration.

  That is, in the same manner as shown in FIG. 3, among the short pulse laser light source 2 that outputs a short pulse laser light having a higher brightness than the molten pool 1 and the short pulse laser light emitted from the short pulse laser light source 2, Nd A high-intensity illumination optical system 8a for irradiating the welded portion with the short pulse laser beam 3 based on the second harmonic of the -YAG laser for illumination, and a high-speed shutter 5 for photographing the welded portion. In a configuration comprising a camera (CCD camera) 4 and a timing device 6 for synchronizing the irradiation timing of the short pulse laser light source 2 with the opening and closing of the high-speed shutter 5 of the camera 4, the emission of the short pulse laser light source 2 The fundamental wave and the second harmonic wave of the Nd-YAG laser contained in the short pulse laser beam emitted from the short pulse laser light source 2 are separated at the position immediately after the side, and the second harmonic wave is separated. The short pulse laser beam (hereinafter referred to as second harmonic short pulse laser beam) 3 can be emitted toward the high-luminance illumination optical system 8a, and the short pulse laser beam (hereinafter referred to as fundamental wave short) composed of the fundamental wave. A wavelength separation mirror 30 that emits 31) (referred to as a pulsed laser beam) in another direction is provided. Further, the fundamental short pulse laser beam 31 radiated from the wavelength separation mirror 30 is guided to the welded portion, and the fundamental wave short pulse laser beam 31 is shifted from the camera 4 by a required angle as a planar fan beam 32. A light cutting measurement optical system 33 is provided for projecting from the position to a required position of the welded portion within the field of view of the camera 4 to obtain a light cut image at the position.

  More specifically, the short pulse laser light source 2 converts the wavelength of the fundamental wave of the Nd-YAG laser into the second harmonic with the required conversion efficiency, and converts the wavelength-converted second harmonic into the second harmonic. Two short-pulse laser beams 3 and 31 having different wavelengths composed of the remaining fundamental wave are emitted at the same time.

  The wavelength separation mirror 30 is arranged on the optical path of the short pulse laser light emitted from the short pulse laser light source 2, for example, at an angle of 45 °, and the short pulse laser light incident from the short pulse laser light source 2. Among them, the second harmonic short pulse laser beam 3 can be emitted in a direction perpendicular to the incident direction, and the fundamental short pulse laser beam 31 is allowed to pass to the rear surface side in the direction along the incident direction. Can be emitted.

  The high brightness illumination optical system 8a is provided with one end serving as an incident side end at a position where the second harmonic short pulse laser beam 3 emitted from the wavelength separation mirror 30 is incident, The optical fiber 34 is arranged so that the other end side reaches the vicinity of the welded portion, and the lens portion 35 attached to the output side end portion of the optical fiber 34, enters from the wavelength separation mirror 30 and passes through the optical fiber 34. The transmitted second harmonic short pulse laser beam 3 is spread by the lens portion 35 so that it can be irradiated as illumination light with higher brightness than the molten pool 1 toward the molten pool 1 and its peripheral portion in the welded portion. It is.

  The optical section measurement optical system 33 is provided with one end serving as an incident side end at a position where the fundamental short pulse laser beam 31 emitted from the wavelength separation mirror 30 is incident, and the other serving as an emission side. The optical fiber 36 is arranged so that the end side reaches the vicinity of the welded portion, and the lens portion 37 is attached to the output side end portion of the optical fiber 36, and is incident from the wavelength separation mirror 30 and transmitted through the optical fiber 36. The fundamental short pulse laser beam 31 is spread in the shape of a fan by the lens unit 37 to form a fan beam 32 having a higher brightness than the molten pool 1, and the welding traveling direction from the molten pool 1 in the field of view of the camera 4. Can be projected along a direction perpendicular to the welding progress direction, that is, along a direction substantially perpendicular to the direction in which the groove extends in the butt welding. Note that the short pulse laser beam 31 having a wavelength of 1064 nm generated by the fundamental wave of the Nd-YAG laser projected as the fan beam 32 has a detection sensitivity in the CCD of the camera 4 due to the second harmonic used for high-intensity illumination of the weld. Although it is lower than the short pulse laser beam 3 having a wavelength of 532 nm, the fundamental short pulse laser beam 31 only needs to be spread in a plane as the fan beam 32. Therefore, the second harmonic short pulse laser beam 3 is used. It is possible to project on the base material 12 as intensity | strength which can fully be detected with respect to the camera 4 which image | photographs the area | region illuminated by.

  Further, as shown in FIG. 1 (a), the camera 4 may be provided with a sharp cut filter 38 that selectively transmits a wavelength longer than 460 nm. When the sharp cut filter 38 is mounted, the scattered light such as plasma light generated in the welded portion is selectively cut without reducing visual information by the second harmonic short pulse laser light 3 and the fundamental short pulse laser light 31. it can. When the camera 4 having a color CCD is used as the camera 4, the molten pool 1 that is illuminated with high brightness by irradiation of the second harmonic short pulse laser beam 3 of the Nd-YAG laser and The peripheral image can be obtained as a green image, and at the same time, the light that is originally white light can be displayed as a yellow image on the obtained image.

  Other configurations are the same as those shown in FIG. 3, and the same components are denoted by the same reference numerals.

  When the weld visualization device of the present invention is used, the second harmonic short pulse laser beam 3 is brighter than the molten pool 1 toward the molten pool 1 formed on the base material 12 by the laser welding torch 11. Is irradiated in a pulsed manner as a simple illumination. The high-speed shutter 5 of the camera 4 is opened and closed by the timing device 6 so as to synchronize with the timing at which the emission intensity equal to or higher than the laser scattered light is given to the molten pool 1 and its peripheral part by the irradiation of the second harmonic short pulse laser light 3. Therefore, as in the conventional weld visualization device as shown in FIG. 3, the light from the molten pool 1 illuminated with high brightness is incident on the camera 4 while other harmful effects such as laser scattered light. The light is cut and the amount of incident light is greatly reduced. Further, harmful light is also cut by the sharp cut filter 38, so that halation occurs on the monitor 13 as shown in FIG. Thus, visible observation of the weld pool 1 and its peripheral portion in the welded portion is performed.

  At the same time, at the position immediately before the welding progress direction of the molten pool 1 within the field of view of the camera 4, the fan beam 32 by the fundamental short pulse laser beam 31 is projected, so that a bright line appears on the surface of the base material 12 in the weld. As a result, a light section image 39 is formed. This light cut image is taken by the camera 4 as the irradiation timing of the short pulse laser light source 2 and the high-speed shutter 5 of the camera 4 are synchronized. At this time, the wavelength of the fundamental short pulse laser beam 31 forming the light section image 39 is 1064 nm, and the second harmonic of the Nd-YAG laser having a wavelength of 532 nm used for high-intensity illumination of the welded portion. Therefore, when the CCD of the camera 4 is a color CCD, the light section image 39 is displayed on the monitor 13 with the second harmonic short pulse as shown in FIG. In the image of the molten pool 1 and its peripheral part obtained in a state of being illuminated with high intensity green by the laser light 3, it is white in terms of characteristics with respect to light in different colors, that is, in the infrared region of the color CCD having a wavelength of 1064 nm. Will be displayed.

  When the CCD of the camera 4 is a monochrome CCD, the light section image 39 is displayed as a bright line in the monitor image.

  As described above, according to the weld visualization device of the present invention, the entire weld zone including the weld pool 1 and its peripheral portion under high-intensity illumination is directly observed using an image photographed by one camera 4. At the same time, it is possible to obtain the light section image 39 at the location immediately before welding in the welded portion. Therefore, it is possible to acquire information on the uneven shape of the weld by analyzing the light cut image 39.

  Further, as the light cut image 39, the light cut image 39 at the position immediately before the welding progress direction of the molten pool 1 can be obtained without being disturbed by the light emission of the molten pool 1. It is possible to eliminate the time lag between the information about the shape of the groove portion obtained based on the groove and the groove portion from which the information is obtained until the groove portion is actually welded.

  Furthermore, the configuration of the weld visualization device according to the present invention can emit, as the short pulse laser light source 2, the short pulse laser beams 3 and 31 having two different wavelengths composed of the second harmonic and the fundamental wave of the Nd-YAG laser. It is sufficient if there is only one short pulse laser light source 2 as described above, and only one camera 4 is required. Further, the irradiation timing of the short pulse laser light source 2 is synchronized with the opening and closing of the high-speed shutter 5 of the camera 4. Since only one timing device 6 is required, it can be manufactured without significantly increasing the cost as compared with the weld visualization device proposed by the present applicant as shown in FIG. It becomes possible.

  Furthermore, the welded portion is illuminated with high-intensity by the short pulse laser beam 3 by the second harmonic of the Nd-YAG laser having a wavelength of 532 nm which is a visible light region, and at the same time, Nd-YAG having a wavelength of 1064 nm which is an infrared region. Since a light-cut image by the laser fundamental wave short pulse laser beam 31 can be obtained, an image suitable for photographing with a CCD camera can be obtained.

  Next, FIGS. 2A and 2B show another embodiment of the present invention. In the same configuration as shown in FIGS. 1A and 1B, an optical fiber 36 and a lens unit 37 are used. Instead of providing an optical system 33 for measuring the optical section which is designed to project the fundamental wave short pulse laser beam 31 as a fan beam 32 onto one surface of the base material 12 of the welded portion, the fundamental wave short pulse laser described above is provided. The light 31 is divided into a plurality of parts, and an optical system 33a for optical cutting measurement is provided so that the fan beam 32 can be projected to a plurality of locations on the surface of the base material 12 in the welded portion.

  More specifically, the optical section measuring optical system 33a emits the optical fiber 36 for transmitting the fundamental short pulse laser beam 31 incident from the wavelength separation mirror 30, as shown in FIG. The incident side end portions of the two branch optical fibers 41a and 41b are connected to the side end portion via the beam splitter 40, and the output side end portions of the branch optical fibers 41a and 41b are connected to the side end portion of FIG. The lens portions 37a and 37b similar to the lens portion 37 shown in FIG. 5 are attached, and the fundamental short pulse laser beam 31 transmitted through the optical fiber 36 is divided into two by the beam splitter 40. In addition to being guided to the branch optical fibers 41a and 41b, as fan beams 32a and 32b at the lens portions 37a and 37b respectively corresponding to the branch optical fibers 41a and 41b, Within the field of view of camera 4, for example, immediately before the position and after the position of the welding direction of the molten pool 1, are also available projected respectively along a direction substantially perpendicular to the welding direction.

  Other configurations are the same as those shown in FIGS. 1A and 1B, and the same components are denoted by the same reference numerals.

  According to the present embodiment, the entire welded portion illuminated with high-intensity by the second harmonic short pulse laser beam 3 is displayed on the image of the monitor 13 as in the embodiment shown in FIGS. At the same time, it is possible to obtain information on the shape of the groove portion immediately before welding from the light cut image 39a by the fan beam 32a projected to the position immediately before the welding progress direction of the molten pool 1, Furthermore, information on the uneven shape of the bead formed immediately after welding can be obtained at the same time by the light cut image 39b by the fan beam 32b projected to the position immediately after the welding progress direction of the molten pool 1.

  The present invention is not limited to the above embodiment, and the position where the fan beam 32 is projected by the fundamental short pulse laser beam 31 in the embodiment shown in FIGS. It may be set at a position immediately above 1 or immediately after the welding progress direction of the molten pool 1. In this case, it is possible to obtain information regarding the molten pool 1 and the uneven shape of the beads formed immediately after welding. In the embodiment shown in FIGS. 2 (a) and 2 (b), the fan beams 32a and 32b generated by the fundamental short pulse laser beam 31 are projected to two positions, the position immediately before and immediately after the welding progress direction of the molten pool 1. As shown above, the optical short measuring laser beam 31 is divided into a plurality of divisions of three or more in the optical system for optical cutting measurement, and a fan beam is projected to three or more places in the field of view of the camera 4 to each of the individual pieces. A light-cut image at a place may be obtained. In this case, as long as the position where each fan beam is projected is within the field of view of the camera 4, it can be set at an arbitrary position such as forward or backward in the welding progress direction of the molten pool 1 or directly above the molten pool 1.

  As the short pulse laser light source 2, the wavelength of the fundamental wave of the Nd-YAG laser is converted to the second harmonic wave with a required conversion efficiency, and the short pulse laser beam by the fundamental wave that remains without being converted to the second harmonic wave. 3 and 31 are output, but laser light sources other than Nd-YAG lasers can be used as long as they can output two short-wavelength lasers having different luminance than the scattered light emitted from the molten pool 1 during welding. In addition, a laser light source that simultaneously outputs a short pulse laser beam of any two wavelengths out of the required laser fundamental wave and each harmonic obtained by wavelength conversion of the fundamental wave is used. May be. Furthermore, the short pulse laser beam 3 for irradiation from the high-brightness illumination optical system 8a and the short pulse laser beam 31 for irradiation as a fan beam from the optical section measurement optical systems 33 and 33a require the cost required for the apparatus. Although it is preferable to output from the same short pulse laser light source 2 from the viewpoint of suppressing the above, it may be output from individual short pulse laser light sources synchronized in irradiation timing.

  The high-intensity illumination optical system 8a and the light-cutting measurement optical systems 33 and 33a all use optical fibers 34, 36, 41a, and 41b as laser light transmission paths. Any configuration such as using a mirror or using both a mirror and an optical fiber may be used as long as it can lead to a desired irradiation point. As the wavelength separation unit, one wavelength separation mirror 30 is shown. However, if the short pulse laser beams of two different wavelengths emitted from the short pulse laser light source 2 can be separated for each wavelength, a plurality of wavelengths can be obtained. A separation mirror may be combined, or a wavelength separation device other than the wavelength separation mirror 30 may be used. The camera 4 is preferably equipped with a sharp cut filter 38, but may not be provided.

The weld visualization device of the present invention is not limited to the type of laser light used for welding, such as YAG laser or CO ₂ laser, and can be applied to observation of welds in various laser welding.
Furthermore, the present invention can be applied to observation of a welded portion by various welding methods such as plasma welding and arc welding. Of course, various changes can be made without departing from the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS One Embodiment of the welding part visualization apparatus of this invention is shown, (A) is a perspective view which shows the outline | summary of the whole, (B) is a figure which shows the image displayed on a monitor. 4A and 4B show another embodiment of the present invention, in which (A) is a perspective view showing an overview of the whole, and (B) shows an image displayed on a monitor. It is a schematic diagram which shows the welding part visualization apparatus which the present applicant has proposed conventionally. It is a perspective view which shows the outline | summary of the arc welding monitoring apparatus which employ | adopted the optical cutting method proposed conventionally. FIG. 5 shows image information obtained by the apparatus of FIG. 4, (A) is a light section image taken by a cross-sectional shape measuring camera, and (B) is a welding arc and molten pool photographed by an arc camera. (C) shows images obtained by combining the images (a) and (b).

Explanation of symbols

1 Weld pool (welded part)
2 Short pulse laser light source 3 Second harmonic short pulse laser light (short pulse laser light)
4 Camera 5 High-speed shutter 6 Timing device 8a Optical system for high-intensity illumination 30 Wavelength separation mirror (wavelength separation section)
31 Fundamental Short Pulse Laser Light (Short Pulse Laser Light)
32, 32a, 32b Fan beam 33, 33a Optical system for optical cutting measurement

Claims (5)

  An optical system for high-intensity illumination for irradiating a welded part with short-pulse laser light having a brightness higher than that emitted from the welded part, and a short-pulse laser beam having a wavelength different from that of the optical system for high-intensity illumination An optical system for optical cutting measurement that irradiates the welded portion at a timing synchronized with the short-pulse laser light of the optical system for high-intensity illumination in the form of a fan beam that is brighter than the light emitted from the welded portion, and And a camera comprising a high-speed shutter for photographing the welded portion, and a timing device for synchronizing the irradiation timing of the short pulse laser light from each optical system with the opening and closing of the high-speed shutter of the camera A weld visualization device characterized by comprising:   The short pulse laser light emitted from the short pulse laser light source is output to the emission side of the short pulse laser light source that simultaneously outputs two short wavelength laser light beams having different wavelengths so as to have higher brightness than the light emitted from the welded portion. A high-brightness illumination optical system for providing a wavelength separation unit for separating each wavelength, and irradiating the welded part with a short-pulse laser beam having one wavelength that is wavelength-separated by the wavelength separation unit. An optical system for optical cutting measurement that irradiates the welded portion with a short pulse laser beam of the other wavelength in the form of a fan beam, and a camera provided with a high-speed shutter for photographing the welded portion, and Visible welds characterized by comprising a timing device that synchronizes the irradiation timing of the short pulse laser light from the short pulse laser light source with the opening and closing of the high-speed shutter of the camera. Apparatus.   The weld visualization device according to claim 2, wherein the short pulse laser light source has a function of simultaneously emitting two wavelengths of a fundamental wave generated by laser oscillation and each harmonic wave obtained by wavelength conversion of the fundamental wave.   The welded portion visualizing device according to claim 3, wherein the short pulse laser light source converts the wavelength of the fundamental wave of the Nd-YAG laser with a required conversion efficiency and emits the fundamental wave and the second harmonic simultaneously. .   The welded part according to claim 2, 3 or 4, wherein the optical system for measuring the light section has a function of projecting short pulse laser light incident from the wavelength separation part as a plurality of fan beams to a plurality of locations in the welded part. Visualization device.

Images