JP2017181048A - Laser-ultrasonic measurement device, laser-ultrasonic measurement method, and welding device and welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To grasp the shape of a solid-liquid interface and its size by laser-ultrasonic measurement.SOLUTION: According to an embodiment of the present invention, a laser-ultrasonic measurement device 14 comprises a transmission laser light source 30, a transmission optical mechanism 31, a reception laser light source 32, a reception optical mechanism 33, an interferometer 34, a data analysis mechanism 35, an imaging device 36, a transmission laser movement mechanism 37, a reception laser movement mechanism 38, and a measurement control unit 39. With one of a transmission laser irradiation point 42 and a reception laser irradiation point 44 defined as a fixed irradiation point and the other defined as a moving irradiation point, a pulsed laser beam 41 for transmission or a laser beam 43 for reception is radiated to a plurality of positions of the moving irradiation point and one place of the fixed irradiation point on each of a plurality of radiation direction lines centering on a prescribed center point on a first surface 21. The imaging device 36 displays the position of a solid-liquid interface 25 along each of the radiation direction lines.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to an apparatus and method for laser ultrasonic measurement, and a welding apparatus and welding method using the apparatus and method.

  In welding involving a metal melting phenomenon, defects may occur due to construction, and therefore, inspection of defects after welding is necessary. In the defect inspection after welding, a penetration inspection test is widely used as a surface inspection, and an ultrasonic inspection test and a radiation transmission test are widely used as a volume inspection. In addition, in order to perform an inspection during welding, an inspection method using a laser ultrasonic method capable of inspecting a high-temperature inspection object in a non-contact manner is known.

  For example, a method for performing a volume inspection of a welded part during welding is known. In this method, it is possible to detect a welding defect existing in a welded portion that has become a solid phase immediately after welding by irradiating a welding laser on a welding bead and a receiving laser on a base material. As mentioned above, the importance of defect inspection is widely recognized, but if the shape change of the weld pool can be measured during welding, it will be a clue to know the welding process and the mechanism of weld defect occurrence, and the results obtained It is possible to further improve the welding quality by feeding back to the welding conditions.

Japanese Patent No. 5651533 Japanese Patent No. 4090620 Japanese Patent No. 4086938

  As a method for quality control of welding, during the automatic welding of TIG welding, based on the image of the surveillance camera, by recognizing the change in the uneven shape on the front of the molten pool, the electrode aiming position control, wire aiming position control, welding conditions A method of performing control is known. However, in order to measure the weld pool shape during welding in situ, it is necessary to measure the high-temperature solid / liquid interface (solid-liquid interface) in-process.

  As another method, there is known a method in which a part of one surface to be measured has a liquid phase and an interface between the solid phase and the liquid phase is measured by a laser ultrasonic method. The laser ultrasonic method is a method of transmitting and receiving ultrasonic waves using an ultrasonic excitation laser, an ultrasonic receiving laser, and an interferometer, and can perform non-destructive inspection remotely without contact, so it is in a high temperature state. It is effective for measurement of the measurement target. However, this prior art system performs two-dimensional scanning with the distance between the ultrasonic transmission position and reception position fixed. In this method, depending on the shape of the molten pool to be formed, there is a possibility that a reflected wave cannot be acquired due to the positional relationship between the ultrasonic transmission position and reception position and the solid-liquid interface of the molten pool.

  Embodiments of the present invention have been made in view of the above circumstances, and are a laser ultrasonic measurement device and a laser ultrasonic measurement method capable of accurately capturing the shape and size of a solid-liquid interface, and those An object of the present invention is to provide a welding apparatus and a welding method using the metal.

  In the laser ultrasonic measurement device according to the embodiment of the present invention, the solid phase portion is formed in contact with the first surface, and the liquid phase portion is in contact with a part of the second surface opposite to the first surface. Is a laser ultrasonic measurement apparatus for measuring the position of the solid-liquid interface of an object in which a solid-liquid interface is formed between the solid-phase part and the liquid-phase part, and excites ultrasonic waves A transmission laser light source for generating a transmission pulse laser light, a transmission optical mechanism for guiding the transmission pulse laser light generated by the transmission laser light source to a transmission laser irradiation point on the first surface, and a reception laser light A receiving laser light source, and a receiving optical mechanism for condensing the receiving laser light reflected by irradiating the receiving laser light generated by the receiving laser light source on the receiving laser irradiation point on the first surface; The received laser beam condensed by the receiving optical mechanism A data analysis mechanism for analyzing the obtained ultrasonic signal to determine the position of the solid-liquid interface, a transmission laser moving mechanism for moving the transmission laser irradiation point along the first surface, and the reception laser irradiation A reception laser moving mechanism that moves a point along the first surface; and a measurement control unit that controls the transmission laser light source, the reception laser light source, the transmission laser movement mechanism, and the reception laser movement mechanism, The measurement control unit has one of the transmission laser irradiation point and the reception laser irradiation point as a fixed irradiation point, the other as a moving irradiation point, and a plurality of centers around a predetermined center point on the first surface. The transmission pulse laser beam or the reception is applied to a plurality of the moving irradiation points along each of the radiation direction lines and one fixed irradiation point defined for each of the plurality of radiation direction lines. It is configured to emit a laser beam, characterized by.

  The welding apparatus according to an embodiment of the present invention includes the laser ultrasonic measurement apparatus, a welding torch that welds the second surface of the object to form a molten pool as the liquid phase part, and the welding A welding control unit that controls a welding condition of a torch, wherein the welding control unit determines the welding condition based on the position of the solid-liquid interface obtained from the laser ultrasonic measurement device. It is comprised so that it may control.

  Moreover, the laser ultrasonic measurement method according to the embodiment of the present invention includes the second surface of the object including the solid phase portion and the first surface and the second surface opposite to the first surface. A solid-liquid interface forming step of forming a liquid-phase part on a part of the surface to form a solid-liquid interface between the solid-phase part and the liquid-phase part; and generating a first pulse laser beam for transmission A transmission laser irradiation step for irradiating a transmission laser irradiation point on the surface of the laser beam, and a reception laser for condensing the reception laser light reflected by irradiating the reception laser irradiation point on the first surface with the reception laser irradiation point A condensing step, and a data analysis step for analyzing the ultrasonic signal obtained based on the receiving laser beam condensed in the receiving laser condensing step to obtain the position of the solid-liquid interface, The transmitting laser irradiation step and the receiving laser In the optical step, one of the transmission laser irradiation point and the reception laser irradiation point is a fixed irradiation point, the other is a moving irradiation point, and a plurality of radiations centered on a predetermined center point on the first surface The transmitting pulse laser beam or the receiving laser beam is irradiated to the plurality of moving irradiation points along each of the direction lines and one fixed irradiation point defined for each of the plurality of radiation direction lines. It is characterized by this.

  Moreover, the welding method according to the embodiment of the present invention welds the second surface of the object while controlling welding conditions based on the position of the solid-liquid interface obtained by the laser ultrasonic measurement method. It is characterized by doing.

  According to the embodiments of the present invention, a laser ultrasonic measurement device and a laser ultrasonic measurement method capable of accurately capturing the shape and size of a solid-liquid interface, and a welding apparatus and a welding method using the same are provided. can do.

It is a typical elevation sectional view of a welding device containing a laser ultrasonic measuring device concerning one embodiment of the present invention. It is a top view which shows typically the target object relative movement apparatus of the laser ultrasonic measurement apparatus which concerns on one Embodiment of this invention. It is a bottom view which shows an example of the position of the laser irradiation point of the target object in the laser ultrasonic measurement method which concerns on one Embodiment of this invention. It is a typical elevation sectional view showing an imaging field of a solid-liquid interface of a molten pool peripheral part in a laser ultrasonic measurement method concerning one embodiment of the present invention. It is a typical perspective view which shows the imaging area | region of FIG. It is a typical elevation sectional view showing an imaging field of a solid-liquid interface of a molten pool center part in a laser ultrasonic measurement method concerning one embodiment of the present invention. It is a typical perspective view which shows the imaging area | region of FIG. It is an elevation sectional view showing an example of a position of a laser irradiation point of an object in case of butt welding in a laser ultrasonic measurement method concerning one embodiment of the present invention. FIG. 9 is an elevational sectional view showing an example different from FIG. 8 of the position of the laser irradiation point of the object in the case of butt welding in the laser ultrasonic measurement method according to one embodiment of the present invention.

  Hereinafter, a laser ultrasonic inspection apparatus and a laser ultrasonic inspection method according to an embodiment of the present invention, and a welding apparatus and a welding method using these will be described with reference to the drawings.

  FIG. 1 is a schematic sectional elevation view of a welding apparatus including a laser ultrasonic measurement device according to an embodiment. FIG. 2 is a plan view schematically showing an object relative movement device of the laser ultrasonic measurement device according to the embodiment.

  As shown in FIG. 1, a welding apparatus 10 according to this embodiment includes a welding machine 11, a welding torch 12, a welding control unit 13, a laser ultrasonic measurement device 14, and an object relative movement device 15. It is out. Here, the object 20 to be welded is made of metal and has a plate shape, and has a first surface 21 and a second surface 22 that extend in parallel to each other. The welding apparatus 10 performs welding with the welding torch 12 facing the second surface 22 (for example, the upper surface) of the object 20. At that time, a molten pool 23 that is a liquid phase portion is formed on the second surface 22, and a solid-liquid interface 25 is formed as a boundary between the liquid phase portion 23 and the solid phase portion 24. The laser ultrasonic measuring device 14 measures the shape and size of the molten pool 23.

  The laser ultrasonic measurement device 14 includes a transmission laser light source 30, a transmission optical mechanism 31, a reception laser light source 32, a reception optical mechanism 33, an interferometer 34, a data analysis mechanism 35, an imaging device 36, and a transmission. A laser moving mechanism 37, a receiving laser moving mechanism 38, and a measurement control unit 39 are provided.

  The transmission laser light source 30 generates a transmission pulse laser beam 41 that excites the ultrasonic wave 40. The transmission optical mechanism 31 guides the transmission pulse laser beam 41 generated by the transmission laser light source 30 to the transmission laser irradiation point 42 on the first surface 21. The reception laser light source 32 generates reception laser light 43 for receiving the ultrasonic waves reflected by the solid-liquid interface 25 by the ultrasonic waves 40 that are excited by the transmission pulse laser light 41 and propagated through the object 20. The reception optical mechanism 33 irradiates the reception laser irradiation point 44 on the first surface 21 with the reception laser light 43 generated by the reception laser light source 32 and also receives the reception laser light 43 reflected by the reception laser irradiation point 44. Condensate.

  The interferometer 34 interferometrically measures the laser light collected by the receiving optical mechanism 33 to obtain an ultrasonic signal. The data analysis mechanism 35 records and analyzes the ultrasonic signal obtained by the interferometer 34 and obtains the position of the solid-liquid interface 25. The imaging device 36 displays the position of the solid-liquid interface 25 obtained by the data analysis mechanism 35 as a two-dimensional or three-dimensional image.

  The transmission laser moving mechanism 37 moves (scans) the transmission laser irradiation point 42 along the first surface 21. The reception laser moving mechanism 38 moves (scans) the reception laser irradiation point 44 along the first surface 21. The transmission laser movement mechanism 37 and the reception laser movement mechanism 38 are, for example, galvano scanner structures that operate integrally with the transmission optical mechanism 31 and the reception optical mechanism 33, respectively.

  The measurement control unit 39 controls the transmission laser light source 30, the reception laser light source 32, the transmission laser movement mechanism 37, the reception laser movement mechanism 38, and the like.

  As a laser used for the transmission laser light source 30 and the reception laser light source 32, for example, an Nd: YAG laser, a CO2 laser, an Er: YAG laser, a titanium sapphire laser, an alexandrite laser, a ruby laser, an excimer is used depending on the type of the object 20. A laser or the like can be used.

  As the interferometer 34, for example, a Michelson interferometer, a homodyne interferometer, a heterodyne interferometer, a Fizeau interferometer, a Mach-Zehnder interferometer, a Fabry-Perot interferometer, a photorefractive interferometer, or the like can be used.

  The laser ultrasonic measurement device 14 further includes a thermometer 50 for measuring the temperature inside the object 20. The thermometer 50 includes a temperature sensor 51 attached to the object 20 and a thermometer main body 52 connected to the temperature sensor 51. The thermometer main body 52 is configured to send a signal representing the temperature inside the object 20 obtained by the temperature sensor 51 to the data analysis mechanism 35.

  The object relative movement device 15 is a device for moving the object 20. By the object relative movement device 15, the distance between the first surface 21 of the object 20 and the transmission optical mechanism 31, the distance between the first surface 21 and the reception optical mechanism 33, the second of the object 20 The object 20 can be moved in the direction of arrow A in FIG. 2 while keeping the distance between the surface 22 and the welding torch 12 constant. By moving the object 20 during execution of welding, a molten pool 23 is formed on the second surface 22 of the object 20 directly below the welding torch 12, and the molten pool 23 is moved from a position directly below the welding torch 12. As the distance increases, the molten pool 23 solidifies. As a result, the weld line 16 is formed on the second surface 22 of the object 20.

  Here, as a welding method using the welding machine 11 and the welding torch 12, for example, TIG welding, MAG welding, MIG welding, covering arc welding, submerged arc welding, inert gas arc welding, carbon dioxide arc General arc welding such as welding, plasma arc welding, electroslag welding, general resistance welding such as spot welding and seam welding, gas welding, thermite welding, electron beam welding, laser welding, etc. It is possible to apply.

  FIG. 3 is a bottom view showing an example of the position of the laser irradiation point of the object in the laser ultrasonic measurement method according to the embodiment. Here, it is assumed that the first surface 21 of the flat object 20 is downward and the second surface 22 is upward. As described above, the molten pool 23 is formed on the second surface 22 of the object 20, and the transmission laser irradiation point 42 and the reception laser irradiation point 44 are taken on the first surface 21 that is the back side, that is, the bottom surface.

  The solid-liquid interface 25 of the molten pool 23 usually has a shape close to a downwardly convex hemisphere. Therefore, in order to accurately grasp the three-dimensional shape of the solid-liquid interface 25, a plurality of transmissions are respectively performed on each radial line passing through the center around the position directly below the center position of the molten pool 23. A laser irradiation point 42 is taken. Further, one receiving laser irradiation point 44 is taken on each radial line. Here, a plurality of transmission laser irradiation points 42 arranged in each radiation direction are referred to as a radiation direction row 60. The innermost transmission laser irradiation point 42 of each radial direction row 60 is inside the outer periphery of the molten pool 23, and the outermost transmission laser irradiation point 42 of each radial direction row 60 is outside the outer periphery of the molten pool 23. Set to be.

  The center position of the weld pool 23 can be set as a position directly below the welding torch 12 (FIG. 1). The size of the molten pool 23 can be estimated based on past experience values and the like.

  In the example of FIG. 3, five transmission laser irradiation points 42 are arranged in each radial direction row 60. However, the number is not limited as long as the number is two or more. In the example of FIG. 3, eight radial direction rows 60 are set at 45 degree intervals, but the number of each radial direction row 60 may be any number as long as it is two or more. However, the circumferential interval between the radial rows 60 is generally preferably equal. In addition, the interval between the transmission laser irradiation points 42 in each radial direction row 60 is generally preferably equal.

  As shown in FIG. 3, a plurality of transmission laser irradiation points 42 are arranged in an annular shape near the center of each radial direction row 60 around the position directly below the center position of the molten pool 23, and 1 at the center position. The number of receiving laser irradiation points 44 is set. Here, a plurality of transmission laser irradiation points 42 arranged in an annular shape are referred to as an annular row 61. The annular row 61 is set to be inside the outer periphery of the molten pool 23.

  In the example of FIG. 3, the position of the reception laser irradiation point 44 corresponding to each radiation direction column 60 is located between the second and third transmission laser irradiation points 42 from the outside, but is not limited to this. Instead, for example, it may be positioned further outside the outermost transmission laser irradiation point 42.

  As shown in FIG. 3, for each radial direction row 60, it is preferable to arrange the receiving laser irradiation point 44 on the same radial direction line as the radial direction row 60. It does not have to be on the direction line. However, a position close to the radial direction line of the radial direction row 60 is preferable, and in particular, a position closer to other adjacent radial direction rows 60 is preferable.

  At the transmission laser irradiation point 42, an ultrasonic wave propagating in the object 20 is generated by being irradiated with the transmission pulse laser beam 41 and excited by ablation or thermal strain. At this time, particularly in the ablation mode, an irradiation mark remains at the transmission laser irradiation point 42, and if the reception laser beam 43 is irradiated to that position, the reflectance of the reception laser beam 43 decreases, and the light reception necessary for interference measurement is performed. The amount may not be obtained. Therefore, particularly when the ablation mode is used, it is preferable that the transmission laser irradiation point 42 and the reception laser irradiation point 44 do not overlap each other.

  FIG. 4 is a schematic sectional elevation view showing an imaging region of a solid-liquid interface around the molten pool in the laser ultrasonic measurement method according to the embodiment. FIG. 5 is a schematic perspective view showing the imaging region of FIG.

  As shown in FIG. 4 and FIG. 5, a plurality of transmission laser irradiation points 42 in one radial direction row 60 are irradiated with a transmission pulse laser beam 41, and one reception laser irradiation point 44 corresponding to them is used for reception. Laser light 43 is irradiated. However, the plurality of transmission laser irradiation points 42 are irradiated with the transmission pulse laser beam 41 at the same time, and scanning is performed at different times.

  The movement of the transmission laser irradiation point 42 and the reception laser irradiation point 44 described above is performed by the transmission laser movement mechanism 37, the reception laser movement mechanism 38, and the like. The operations of the transmission laser light source 30, the reception laser light source 32, the transmission laser moving mechanism 37 and the receiving laser moving mechanism 38, the data analysis mechanism 35 and the imaging device 36 corresponding to them are automatically controlled by the measurement control unit 39. Is done.

  With the above procedure, the position of the solid-liquid interface 25 along the radial direction row 60 can be measured. Thereby, the solid-liquid interface 25 along one radial direction row 60 can be displayed as the imaging region 62.

  The direction and order of movement (scanning) of the transmission laser irradiation point 42 and the reception laser irradiation point 44 are arbitrary. For example, in the case of the radial direction column 60, the transmission laser irradiation point 42 is set as the center point of each radial direction column 60. It may move from a near position to a direction far from the center point, or conversely, it may move from a position far from the center point to a position close to the center point.

  Since the solid-liquid interface 25 can be similarly displayed as the imaging region 62 for the plurality of radial direction columns 60, the three-dimensional (three-dimensional) shape and size of the solid-liquid interface 25 are displayed as a whole. Can do.

  FIG. 6 is a schematic sectional elevation view showing an imaging region of a solid-liquid interface at the center of the molten pool in the laser ultrasonic measurement method according to the embodiment. FIG. 7 is a schematic perspective view showing the imaging region of FIG.

  As shown in FIGS. 6 and 7, a plurality of transmission laser irradiation points 42 in the annular array 61 are irradiated with transmission pulse laser light 41, and one reception laser irradiation point 44 corresponding thereto is received with the reception laser light. By irradiating 43, the position of the solid-liquid interface 25 along the annular row 61 can be measured. Thereby, the solid-liquid interface 25 along the annular array 61 can be displayed as the imaging region 63.

  By connecting the solid-liquid interface 25 along the plurality of radial direction rows 60 and one annular row 61, the three-dimensional (three-dimensional) shape and size of the solid-liquid interface 25 can be displayed as a whole. it can.

  As described above, the temperature sensor 51 is attached to the object 20, and a signal representing the temperature inside the object 20 is sent to the data analysis mechanism 35. In general, the velocity of ultrasonic waves propagating in the object 20 changes according to the temperature inside the object 20. The data analysis mechanism 35 can more accurately determine the three-dimensional shape and size of the solid-liquid interface 25 by correcting the change in the ultrasonic velocity due to the temperature change.

  Furthermore, a signal of the shape and size of the molten pool 23 obtained from the data analysis mechanism 35 is sent to the welding control unit 13, whereby the welding machine 11 can be controlled to change the welding conditions.

  A period for completing the laser irradiation of all the transmission laser irradiation points 42 and the reception laser irradiation points 44 shown in FIG. As a display cycle that is a cycle for updating imaging by the imaging device 36, for example, one movement cycle can be made the same as one display cycle. As another example, one display cycle is made shorter than one movement cycle, and for example, each time the laser irradiation is completed in each radial direction row 60 or annular row 61 shown in FIG. You can also As yet another example, the display content for each point can be updated based on the data for each transmission laser irradiation point 42.

  In the above description, in each of the radial direction rows 60 and the annular row 61, one reception laser irradiation point 44 is set as a fixed irradiation point, and a plurality of transmission laser irradiation points 42 are set as moving irradiation points. As another example, with these relations reversed, in each radial direction row 60 and annular row 61, a plurality of receiving laser irradiation points 44 are used as moving irradiation points, and a single transmission laser irradiation point 42 is used as fixed irradiation. It is good also as a point. However, in this case, it is preferable that the irradiation with the transmission pulse laser beam 41 is performed in the thermal strain mode instead of the irradiation in the ablation mode where the irradiation trace remains.

  In the above description, the object 20 is moved by the object relative movement device 15. As another example, the object 20 may be fixed, and the welding torch 12, the transmission optical mechanism 31, and the reception optical mechanism 33 may be integrally moved relative to the object 20.

  In the above description, as shown in FIG. 3, the radial direction rows 60 have the same length. This is particularly suitable when the outer shape of the molten pool 23 is circular. However, for example, when the molten pool 23 extends downstream along the weld line 16, the shape and size of the molten pool 23 can be reduced by particularly increasing the radial direction row 60 in the extending direction. It can be measured more accurately.

  FIG. 8 is an elevational sectional view showing an example of the position of the laser irradiation point of the object in the case of butt welding in the laser ultrasonic measurement method according to one embodiment of the present invention. As shown in FIG. 8, in the case of welding with a groove 70 and a back wave 71, it is difficult to take the transmission laser irradiation point 42 and the reception laser irradiation point 44 directly below the welding torch 12 (see FIG. 1). . In that case, the laser irradiation of the circular column 61 shown in FIG. In this case, in FIG. 8, the transmission laser irradiation point 42 and the reception laser irradiation point 44 are taken in the same direction as viewed from the central point directly below the welding torch 12.

  FIG. 9 is an elevational sectional view showing an example different from FIG. 8 of the position of the laser irradiation point of the object in the case of butt welding in the laser ultrasonic measurement method according to one embodiment of the present invention. The case of FIG. 9 is a modification of the case of FIG. 8, and the transmission laser irradiation point 42 and the reception laser irradiation point 44 are positioned at opposite sides when viewed from the central point directly below the welding torch 12.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

10: Welding device, 11: Welding machine, 12: Welding torch, 13: Welding control unit, 14: Laser ultrasonic measuring device, 15: Object relative movement device, 16: Welding line, 20: Object, 21: No. 1 surface 22: second surface 23: molten pool (liquid phase part) 24: solid phase part 25: solid-liquid interface 30: transmission laser light source 31: transmission optical mechanism 32: reception laser light source 33: reception optical mechanism, 34: interferometer, 35: data analysis mechanism, 36: imaging device, 37: transmission laser movement mechanism, 38: reception laser movement mechanism, 39: measurement control unit, 40: ultrasonic wave, 41 : Transmission pulse laser beam, 42: Transmission laser irradiation point, 43: Reception laser beam, 44: Reception laser irradiation point, 50: Thermometer, 51: Temperature sensor, 52: Thermometer body, 60: Radiation direction column 61: an annular column, 62: imaging region, 63: imaging region, 70: groove, 71: penetration

Claims (6)

A solid phase portion is formed in contact with the first surface, a liquid phase portion is formed in contact with a part of the second surface opposite to the first surface, and the solid phase portion and the liquid phase portion A laser ultrasonic measurement device for measuring the position of the solid-liquid interface of an object in which a solid-liquid interface is formed,
A transmission laser light source for generating a transmission pulse laser beam for exciting ultrasonic waves;
A transmission optical mechanism for guiding the transmission pulse laser beam generated by the transmission laser light source to a transmission laser irradiation point on the first surface;
A receiving laser light source for generating a receiving laser beam;
A receiving optical mechanism for condensing the receiving laser beam reflected by irradiating the receiving laser beam on the first surface with the receiving laser beam generated by the receiving laser light source;
A data analysis mechanism for analyzing the ultrasonic signal obtained based on the received laser light collected by the reception optical mechanism to determine the position of the solid-liquid interface;
A transmission laser moving mechanism for moving the transmission laser irradiation point along the first surface;
A receiving laser moving mechanism for moving the receiving laser irradiation point along the first surface;
A measurement control unit for controlling the transmission laser light source, the reception laser light source, the transmission laser moving mechanism, and the reception laser moving mechanism;
Have
The measurement control unit has one of the transmission laser irradiation point and the reception laser irradiation point as a fixed irradiation point, the other as a moving irradiation point, and a plurality of centers around a predetermined center point on the first surface. A plurality of the moving irradiation points along each of the radiation direction lines and one fixed irradiation point defined for each of the plurality of radiation direction lines is irradiated with the pulse laser beam for transmission or the laser beam for reception Being configured to,
A laser ultrasonic measurement device characterized by the above.   The fixed irradiation point defined for each of the radial direction lines is located closer to the radial direction line than another radial direction line adjacent to the radial direction line in the circumferential direction. The laser ultrasonic measurement apparatus according to 1.   The said measurement control part performs the control which takes the said fixed irradiation point in the said annular ring while taking the said movement irradiation point along the annular ring surrounding the said center point, or characterized by the above-mentioned. The laser ultrasonic measurement device according to claim 2. The laser ultrasonic measurement device according to any one of claims 1 to 3,
A welding torch that welds the second surface of the object to form a molten pool as the liquid phase portion;
A welding control unit for controlling welding conditions of the welding torch;
A welding apparatus comprising:
The welding apparatus is configured to control the welding condition based on the position of the solid-liquid interface obtained from the laser ultrasonic measurement device. The solid phase portion is formed by forming a liquid phase portion on a part of the second surface of the object, the solid phase portion including the first surface and the second surface opposite to the first surface. A solid-liquid interface forming step for forming a solid-liquid interface between the liquid phase part and the liquid phase part;
A transmission laser irradiation step of generating a transmission pulse laser beam and irradiating the transmission laser irradiation point on the first surface;
A receiving laser condensing step of condensing the receiving laser beam reflected by irradiating the receiving laser beam on the first surface with the receiving laser beam;
A data analysis step of analyzing the ultrasonic signal obtained based on the reception laser beam condensed in the reception laser condensing step to determine the position of the solid-liquid interface;
Have
In the transmission laser irradiation step and the reception laser condensing step, one of the transmission laser irradiation point and the reception laser irradiation point is set as a fixed irradiation point, and the other is set as a moving irradiation point. The transmitting pulse laser is applied to the plurality of moving irradiation points along each of the plurality of radiation direction lines centered on the center point and one fixed irradiation point defined for each of the plurality of radiation direction lines. Irradiating light or the receiving laser beam,
A laser ultrasonic measurement method characterized by the above.   A welding method comprising welding the second surface of the object while controlling welding conditions based on the position of the solid-liquid interface obtained by the laser ultrasonic measurement method according to claim 5. .

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