Weld inspection apparatus, shape measurement device, and appearance inspection device

Abstract

This weld inspection apparatus comprises: a transmission laser light irradiation device which irradiates, with transmission laser light, a weld bead on a base material; a reception laser light probe which detects ultrasonic waves that are generated by the transmission laser light and reaches a reception position on the base material; a control device which extracts, from among the ultrasonic waves detected by the reception laser light probe, a bottom surface reflection wave reflected from the bottom surface of the base material, and determines whether an internal defect is present in the weld bead on the basis of the extracted bottom surface reflection wave; and a measurement device which measures an appearance configuration of a portion of the base material that has been irradiated with the transmission laser light. On the basis of the result of measurement by the measurement device, the control device sets a reflection wave extraction condition for extracting a bottom surface reflection wave from among the ultrasonic waves detected by the detection device.

Description

Welding inspection equipment, shape measurement equipment, and appearance inspection equipment

[0001] The present disclosure relates to a welding inspection device, a shape measurement device, and a visual inspection device.

[0002] Japanese Patent Application Laid-Open Publication No. 2023-20336 discloses a welding inspection device for inspecting a welded portion included in a base material. This welding inspection device includes a transmission laser irradiation device that irradiates a transmission laser beam onto the welded portion to excite ultrasonic waves, a detection device that detects ultrasonic waves excited by the transmission laser beam and reaching a receiving position on the base material, and a control device that determines whether or not there is an internal defect in the welded portion. The control device extracts, on a measurement screen called a B-scope, bottom-reflected waves that are reflected and received by the bottom surface of the base material (the surface opposite to the surface irradiated with the transmission laser beam) from the ultrasonic waves that reach the receiving position. If the extracted bottom-reflected wave intensity exhibits a large degree of attenuation, the control device determines that there is an internal defect in the welded portion. The B-scope displays the intensity distribution of ultrasonic waves at the receiving position, with the horizontal axis representing the transmission position, which is the position where the transmission laser beam is irradiated on the welded portion, and the vertical axis representing the time it takes for the ultrasonic waves generated at the transmission position to reach the receiving position.

[0003] Japanese Patent Application Laid-Open No. 2023-20336

[0004] As described above, in the welding inspection device described in JP 2023-20336 A, bottom-reflected waves are extracted on a B-scope from among the ultrasonic waves that reach the receiving position, and if the degree of attenuation of the extracted bottom-reflected wave intensity is large, it is determined that there is an internal defect in the weld.

[0005] However, the thickness and shape of a weld are not constant and can change depending on the welding conditions, etc. When the thickness and shape of a weld change, the external shape (three-dimensional position) of the part of the weld irradiated with the transmitting laser changes, and the propagation distance of the bottom-reflected wave from the transmitting position to the receiving position changes. This changes the arrival time of the bottom-reflected wave, which in turn changes the distribution on the B-scope of the bottom-reflected wave that should be extracted. As a result, there is a concern that the bottom-reflected wave cannot be properly extracted, reducing the inspection accuracy of the weld.

[0006] Therefore, an object of the present disclosure is to enable accurate determination of the presence or absence of internal defects in a weld even when the thickness and shape of the weld vary. Another object of the present disclosure is to enable measurement of the external shape of an object without using a laser scanner.

[0007] (Item 1) A welding inspection device according to the present disclosure is a welding inspection device for inspecting a weld included in an object, and includes a first irradiation device that irradiates the weld with a transmission laser beam and scans a transmission position in the weld, which is the irradiation position of the transmission laser beam, in a first direction, a detection device that detects ultrasonic waves generated by the transmission laser beam and reaching a receiving position on the object, a control device that extracts reflected waves reflected from the underside of the object from the ultrasonic waves detected by the detection device and determines whether or not there is an internal defect in the weld based on the extracted reflected waves, and a measurement device that measures the external shape of the portion of the object irradiated with the transmission laser beam. The control device sets reflected wave extraction conditions for extracting reflected waves from the ultrasonic waves detected by the detection device based on measurement results by the measurement device.

[0008] (2) In the welding inspection device described in (1), the detection device includes a second irradiation device that irradiates the receiving position with a receiving laser light for detecting reflected waves. The control device sets, as a reflected wave extraction condition, an extraction time range that specifies, for each transmission position, a range of arrival time required for ultrasonic waves generated at the transmission position to be reflected by the underside of the object and reach the receiving position, and extracts, from the ultrasonic waves detected by the detection device, ultrasonic waves that arrive within the extraction time range as reflected waves.

[0009] (Item 3) In the welding inspection device described in item 2, the control device shifts the extraction time range toward the side with a longer arrival time as the propagation distance of the reflected wave estimated based on the measurement results by the measuring device becomes longer.

[0010] (4) In the welding inspection device according to the third aspect, the measuring device includes a laser scanner that measures the external shape of the irradiated portion by irradiating the irradiated portion with laser light.

[0011] (Item 5) In the welding inspection device described in item 4, the laser scanner is fixed to a member to which the first irradiation device, the second irradiation device, and the detection device are attached.

[0012] (Item 6) In the welding inspection device according to any one of Items 1 to 3, the first irradiation device generates ablation light at the irradiation portion by irradiating the irradiation portion with a transmission laser light, and the measurement device includes at least one camera that captures an image of the ablation light generated at the irradiated portion.

[0013] (Clause 7) A shape measurement device according to the present disclosure is a shape measurement device that measures the external shape of an object, and includes an irradiation device that irradiates the object with laser light and scans the laser light in a first direction to generate ablation light in the irradiated portion of the object with the laser light, and a measurement device that includes at least one camera that photographs the ablation light generated in the irradiated portion and measures the external shape of the irradiated portion by photographing the ablation light with the at least one camera.

[0014] (Item 8) An appearance inspection device according to the present disclosure includes the shape measurement device according to item 7, and a control device that performs an appearance inspection of an irradiated portion based on a measurement result by the shape measurement device.

[0015] The welding inspection device described above can accurately determine whether or not there is an internal defect in a weld even if the thickness and shape of the weld vary. Also, the appearance inspection device described above can measure the appearance shape of an object without using a laser scanner.

[0016] 1 is a diagram illustrating the configuration of a welding inspection device. FIG. 2 is a diagram illustrating a state when there is no internal defect in a weld bead. FIG. 3 is a diagram illustrating a state when there is an internal defect such as a blowhole in a weld bead. FIG. 4 is a diagram illustrating an example of a B-scope. FIG. 5 is a diagram illustrating a schematic relationship between a transmission position and a detected intensity of a bottom surface reflected wave. FIG. 6 is a diagram illustrating an example of a method for determining the presence or absence of an internal defect in a weld bead. FIG. 7 is a diagram illustrating an example of a setting range for a reflected wave extraction by a control device. FIG. 8 is a flowchart illustrating an example of a procedure for a welding inspection process. FIG. 9 is a diagram illustrating a schematic view of a part of the exterior of a welding inspection device.

[0017] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0018] 1 is a diagram showing the configuration of a welding inspection device 1 according to this embodiment. The welding inspection device 1 includes a transmitting laser source 10, a transmitting laser light irradiator (first irradiator) 12, a receiving laser source 16, a receiving laser light probe (second irradiator) 18, a control device 22, a display device 24, and a measurement device 50.

[0019] This welding inspection device 1 is used, for example, to inspect a weld bead (weld) 6 in a lap fillet weld of thin base materials (objects) 2 and 4. The base materials 2 and 4 are, for example, zinc-plated steel sheets with a thickness of approximately 1 to 2 mm. In the figure, the Y direction indicates the welding progress direction (extension direction of the weld bead), the Z direction indicates the normal direction of the base materials 2 and 4, and the X direction indicates the direction perpendicular to the Y direction and the Z direction. The transmitting laser light emitting device 12 and the receiving laser light probe 18 are fixed to a robot that is movable in the Y direction (welding progress direction), and by moving the robot in the Y direction, the transmitting laser light emitting device 12 and the receiving laser light probe 18 can be moved together in the Y direction relative to the base materials 2 and 4.

[0020] The transmission laser source 10 generates excitation light for generating a transmission laser beam 14 in the transmission laser beam emitting device 12, and outputs the excitation light to the transmission laser beam emitting device 12. The transmission laser source 10 is configured by, for example, an LD (Laser Diode) power supply.

[0021] The transmitting laser beam irradiator 12 receives excitation light from the transmitting laser source 10, generates a transmitting laser beam 14, which is a pulsed laser beam, and irradiates the weld bead 6 to be inspected. The transmitting laser beam irradiator 12 includes, for example, a microchip laser that generates a YAG pulsed laser beam, and a scanning mechanism that can scan the irradiation position of the transmitting laser beam 14 in the X direction. The scanning mechanism includes, for example, a galvanometer mirror whose angle is adjustable, and a driving mechanism that drives the galvanometer mirror.

[0022] The receiving laser source 16 includes a laser interferometer. The receiving laser source 16 generates a receiving laser beam 20 (reference beam) to be irradiated onto the base material 4 of the lower plate, and outputs the beam to the receiving laser beam probe 18. The receiving laser source 16 also receives, from the receiving laser beam probe 18, the reflected beam of the receiving laser beam 20 irradiated onto the base material 4, and detects interference light including the reference beam and the reflected beam, and outputs the interference light to the control device 22.

[0023] The receiving laser light probe 18 irradiates a predetermined receiving point 36 on the base material 4 of the lower plate with the receiving laser light 20. The receiving laser light probe 18 also receives the reflected light from the base material 4 of the receiving laser light 20 irradiated onto the base material 4, and outputs the reflected light to the receiving laser source 16 (laser interferometer).

[0024] This welding inspection device 1 uses a laser ultrasonic method to detect internal defects in a weld bead 6. That is, a transmitting laser beam 14 is irradiated onto the upper surface of the base material 2, 4 including the weld bead 6 to be inspected, generating ultrasonic waves inside the inspection target, and surface vibrations corresponding to the intensity of the ultrasonic waves at a receiving point 36 on the base material 4 to which a receiving laser beam 20 is irradiated are detected by interference light between a reference beam and a reflected beam of the receiving laser beam 20. The presence or absence of an internal defect in the weld bead 6 is then determined based on the detection difference between when the internal defect is present and when it is not present in the weld bead 6.

[0025] The control device 22 includes a CPU (Central Processing Unit), memory (RAM (Random Access Memory) and ROM (Read Only Memory)), and input / output ports for inputting and outputting various signals (all not shown). The CPU loads a program stored in the ROM into the RAM and executes it. The program stored in the ROM describes various processes to be executed by the control device 22.

[0026] The control device 22 controls the transmitting laser source 10 so that the transmitting laser light emitting device 12 generates excitation light for generating the transmitting laser light 14. The control device 22 also controls the transmitting laser light emitting device 12 so that the irradiation position of the transmitting laser light 14 is scanned in the X direction. As a result, the transmitting laser light 14 is irradiated so as to straddle the weld bead 6. The control device 22 also receives from the transmitting laser light emitting device 12 the oscillation timing (pulse irradiation timing) of the transmitting laser light 14 in the transmitting laser light emitting device 12.

[0027] Then, control device 22 acquires from receiving laser source 16 the interference measurement result of receiving laser light 20 by the laser interferometer of receiving laser source 16 as a signal indicating the detection intensity of ultrasonic waves at reception point 36. Control device 22 determines the presence or absence of an internal defect in weld bead 6 based on the detection intensity of ultrasonic waves at reception point 36 acquired from receiving laser source 16. The method of determining the presence or absence of an internal defect in weld bead 6 will be described in detail later.

[0028] The display device 24 is a display for displaying various processing results of the control device 22. The display device 24 displays, for example, a measurement screen called a B-scope, which shows the measurement results of ultrasonic waves within the inspection object by the welding inspection device 1.

[0029] The B-scope displays the distribution of the detected intensity of ultrasonic waves at reception point 36, with the horizontal axis representing the position in the X direction of transmission point 32 (hereinafter also referred to as the "transmission position"), which is the irradiation position of transmission laser beam 14 on weld bead 6, and the vertical axis representing the time it takes for ultrasonic waves generated at transmission point 32 by irradiation with transmission laser beam 14 to reach reception point 36 on base material 4 (hereinafter also referred to as the "ultrasonic wave arrival time" or simply "arrival time"). On the B-scope, the distribution of the detected intensity of ultrasonic waves is represented, for example, by a color map (changes in color or density).

[0030] The control device 22 and the display device 24 are configured by, for example, a PC (Personal Computer).

[0031] <Method for determining the presence or absence of an internal defect in a welded portion> A method for determining the presence or absence of an internal defect in a weld bead 6 using the welding inspection device 1 will be described in detail below. Figures 2 to 6 are diagrams for explaining the principle of detection of an internal defect in a weld bead 6 using the welding inspection device 1.

[0032] 2 is a diagram showing a state when there are no internal defects in the weld bead 6. In this welding inspection device 1, a transmitting laser beam 14 (pulse laser beam) is irradiated onto the upper surfaces of the base materials 2 and 4, including the weld bead 6, to generate ultrasonic waves at a transmission point 32. The ultrasonic waves generated at the transmission point 32 pass through the inside of the weld bead 6, are reflected by the lower surface 5 of the lower base material 4, and then reach a receiving point 36 on the base material 4. The ultrasonic waves reflected by the lower surface 5 and reaching the receiving point 36 (hereinafter also referred to as "lower surface reflected waves") generate micro-vibrations at the receiving point 36 on the base material 4, and are detected by measuring the micro-vibrations using a receiving laser beam 20.

[0033] The transmission points 32 indicated by cross marks are scanned in the X direction using the scanning mechanism of the transmission laser light emitting device 12 (FIG. 1). After measurement at a certain transmission point 32 is completed, scanning is performed in the X direction so that the irradiation position of the transmission laser light 14 becomes the next transmission point 32, and measurement at the next transmission point 32 is performed.

[0034] The receiving point 36 indicated by the symbol O is fixed in the X direction of the base material 4. The greater the distance in the X direction between the transmitting point 32 and the receiving point 36, the longer the propagation distance of the ultrasonic waves from the transmitting point 32 to the receiving point 36, and the intensity of the ultrasonic waves (micro-vibrations on the surface) at the receiving point 36 also decreases due to diffusion attenuation.

[0035] 3 is a diagram showing a state when an internal defect 40 such as a blowhole is present in the weld bead 6. When an internal defect 40 such as a blowhole is present in the weld bead 6, depending on the transmission position, ultrasonic waves generated at the transmission point 32 are divided into a non-passing component 41 that is blocked by the internal defect 40 and scattered without reaching the reception point 36, and a passing component 44 that passes through the internal defect 40 and travels. In this case, the passing component 44 is reflected by the bottom surface 5 of the base material 4 and reaches the reception point 36, but the detected intensity of the bottom surface ultrasonic waves at the reception point 36 is smaller (attenuation is greater) than when the defect 40 is not present. Therefore, the presence or absence of an internal defect 40 in the weld bead 6 can be determined by capturing the attenuation of the detected intensity of the bottom surface ultrasonic waves at the reception point 36.

[0036] Fig. 4 is a diagram schematically illustrating an example of a B-scope displayed on the display device 24. Fig. 4 illustrates an example of a B-scope when there is no internal defect in the weld bead 6.

[0037] As described above, the B-scope displays the distribution of the detected intensity of ultrasonic waves at the receiving point 36, with the transmission position on the horizontal axis and the ultrasonic wave arrival time on the vertical axis. Therefore, the B-scope displays the transmission position, ultrasonic wave arrival time, and ultrasonic wave detection intensity on a single screen. Note that, for ease of understanding, Fig. 4 shows only the distribution of maximum values ​​of the detected intensity of ultrasonic waves at the receiving point 36 as lines L1 and L2. Line L1 shows the distribution of surface waves that travel from the transmitting point 32 through the surface layer of the weld bead 6 and the base material 4 and arrive at the receiving point 36. Line L2 shows the distribution of bottom-reflected waves.

[0038] The ultrasonic waves detected at the receiving point 36 include not only bottom-reflected waves (line L2) but also surface waves (line L1). Because the propagation paths of the bottom-reflected waves and the surface waves are different, the arrival times of the bottom-reflected waves and the surface waves are also different. By utilizing this phenomenon, the bottom-reflected waves (line L2) are extracted from the ultrasonic waves (lines L1 and L2) arriving at the receiving point 36, excluding the surface waves (line L1). Specifically, the welding inspection device 1 sets the range indicated by the dotted enclosing line in FIG. 4 as a "reflected wave extraction range" and extracts ultrasonic waves arriving within the set reflected wave extraction range as bottom-reflected waves. The reflected wave extraction range (the range indicated by the dotted enclosing line in FIG. 4) defines, for each transmission position, the range of arrival times required for ultrasonic waves generated at the transmitting point to be reflected by the bottom surface 5 of the base material 4 and arrive at the receiving point 36.

[0039] Then, the welding inspection device 1 determines whether or not there is a defect 40 in the weld bead 6 using the bottom surface reflected wave extracted as described above.

[0040] 5 is a diagram showing the relationship between the transmission position and the detected intensity of the bottom surface reflected wave. In FIG. 5, line L3 shows the detected intensity of the bottom surface reflected wave when there is no internal defect in the weld bead 6. The detected intensity of the bottom surface reflected wave is attenuated by diffusion attenuation as the value of the transmission position increases (as the transmission point becomes farther from the reception point).

[0041] Line L4 shows the detected intensity of the bottom surface reflected wave when an internal defect is present in the weld bead 6. When the ultrasonic transmission position is greater than X1, the bottom surface ultrasonic wave that arrives at the ultrasonic reception point passes through the internal defect that has occurred in the weld bead 6. At this time, in addition to diffuse attenuation, scattered attenuation also occurs at the internal defect, so the detected intensity of the bottom surface ultrasonic wave (line L4) when an internal defect has occurred is smaller than when there is no internal defect (line L3). In other words, the attenuation of the detected intensity of the bottom surface reflected wave when there is an internal defect is greater than when there is no internal defect.

[0042] 6 is a diagram illustrating an example of a method for determining the presence or absence of an internal defect in a weld bead 6. The welding inspection device 1 determines the presence or absence of an internal defect in the weld bead 6 based on the magnitude of attenuation of the detected intensity of the bottom-reflected wave. That is, the welding inspection device 1 determines that the weld bead 6 does not have an internal defect if the magnitude of attenuation of the detected intensity of the bottom-reflected wave is equal to or less than a predetermined threshold, and determines that the weld bead 6 has an internal defect if the magnitude of attenuation of the detected intensity of the bottom-reflected wave exceeds the threshold. The threshold is appropriately set to a value that can distinguish the presence or absence of an internal defect through a prior evaluation test or the like. The threshold is set for each transmission position, taking into account the degree of diffusion attenuation depending on the transmission position.

[0043] <Setting the Reflected Wave Extraction Range> As described above, the welding inspection device 1 extracts the bottom surface reflected wave on the B-scope, and determines that there is an internal defect in the weld bead 6 if the degree of attenuation of the detected intensity of the extracted bottom surface reflected wave is large.

[0044] However, the thickness (dimension in the Z direction) and shape of the weld bead 6 are not necessarily constant and may change depending on the welding conditions, etc. If the thickness and shape of the weld bead 6 change, the external shape (three-dimensional position) of the portion of the weld bead 6 irradiated with the transmitted laser beam 14 changes, and therefore the propagation distance of the bottom-surface reflected wave from the transmission point 32 to the reception point 36 changes. This changes the arrival time of the bottom-surface reflected wave, which may affect the distribution of the bottom-surface reflected wave to be extracted on the B-scope. Therefore, in automating welding inspection, it is desirable to set the reflected wave extraction range taking into account the external shape (three-dimensional position) of the portion of the weld bead 6 irradiated with the transmitted laser beam 14.

[0045] In view of the above, the welding inspection device 1 according to this embodiment includes a measuring device 50 for measuring the external shape of the portion of the base material 2, 4, including the weld bead 6, irradiated with the transmitted laser beam 14, as shown in FIG. The measuring device 50 is configured by a laser scanner that measures the shape (three-dimensional position) of the irradiation line (hereinafter also referred to as the "irradiation line") by irradiating a line connecting transmission points aligned in the X direction with a laser beam 52 separate from the transmitted laser beam 14. The measuring device 50 outputs a signal indicating the measurement result to the control device 22. The control device 22 then sets a reflected wave extraction range using the measurement result of the measuring device 50.

[0046] 7 is a diagram showing an example of how the control device 22 sets the reflected wave extraction range. The arrival time of the bottom-reflected wave increases as the transmission point moves farther away from the reception point. Therefore, assuming that the height of the transmission point is constant, the arrival time of the bottom-reflected wave is approximately proportional to the distance from the transmission point to the reception point. However, in reality, since the weld bead 6 has thickness, when the transmission point is located above the weld bead 6, the arrival time of the bottom-reflected wave increases toward the long-term side. This increase in arrival time depends on the thickness of the weld bead 6. In other words, the thicker the weld bead 6, the greater the increase in the arrival time of the bottom-reflected wave.

[0047] Therefore, control device 22 sets the reflected wave extraction range based on the shape data of the irradiation line measured by measuring device 50. Specifically, control device 22 shifts the reflected wave extraction range toward the longer time side as the propagation distance of the bottom surface reflected wave estimated based on the shape data of the irradiation line measured by measuring device 50 becomes longer. As a result, for example, as shown in FIG. 7 , the reflected wave extraction range at the bead position when weld bead 6 is a convex bead (lower row) is shifted to bulge toward the longer time side compared to the reflected wave extraction range at the bead position when weld bead 6 is a relatively flat, normal bead (upper row).

[0048] By setting the reflected wave extraction range based on the shape data of the irradiation line in this way, it is possible to appropriately extract the bottom surface reflected wave even if the thickness or surface shape of the weld bead 6 changes.

[0049] FIG. 8 is a flowchart showing an example of a procedure for welding inspection processing by the welding inspection device 1.

[0050] The control device 22 controls the scanning mechanism of the transmission laser light irradiator 12 so as to irradiate the transmission laser light 14 onto the current transmission point on the inspection object (step S10). The number, positions, and irradiation order of the transmission points arranged on the irradiation line for one scan are predetermined. The control device 22 identifies the current transmission point from among the multiple transmission points arranged on the irradiation line for one scan, and controls the scanning mechanism so as to irradiate the transmission laser light 14 onto the identified current transmission point.

[0051] Next, the control device 22 controls the receiving laser source 16 so that the receiving laser beam 20 is irradiated onto the receiving point (step S15). The receiving point is fixed at a predetermined position in the X direction. The timing of irradiating the receiving laser beam 20 is not limited to after irradiation of the transmitting laser beam 14, but may be before irradiation of the transmitting laser beam 14 or simultaneously with the start of irradiation of the transmitting laser beam 14.

[0052] The receiving laser source 16 receives the reflected light of the receiving laser light 20 irradiated onto the base material 4 from the receiving laser light probe 18, and measures the interference between the reflected light and the receiving laser light 20 (reference light) irradiated onto the base material 4 using a laser interferometer (step S20). This allows the arrival time of the ultrasonic wave at the current transmission point and the reception intensity of the ultrasonic wave at the reception point to be detected.

[0053] Next, the control device 22 determines whether one scan of the transmission laser beam 14 has been completed (step S25). Specifically, it determines whether the detected intensity of the ultrasonic waves at the reception points has been measured for all transmission points for one scan. If one scan has not been completed (NO in step S25), the control device 22 updates the irradiation position (transmission point) of the transmission laser beam 14 to the next position (step S30). Thereafter, the process returns to step S10, and the processes of steps S10 to S30 are repeated until scanning of one line is completed.

[0054] If one scan is completed in step S25 (YES in step S25), the control device 22 executes a process of creating a B-scan (step S35). Specifically, the control device 22 creates a B-scan that displays the distribution of detection intensities for the measurement results (ultrasound wave arrival times and detection intensities for each transmission position) for one scan obtained by repeating the processes of steps S10 to S30, with the transmission position on the horizontal axis and the ultrasound arrival time on the vertical axis. The B-scan may be displayed on the display device 24.

[0055] Next, the control device 22 controls the measuring device 50 to measure the shape of the irradiation line for one scan (step S40). The timing of measuring the shape of the irradiation line for one scan (step S40) is not limited to after one scan is completed, but may be before the start of one scan or during one scan.

[0056] Then, the control device 22 sets the reflected wave extraction range based on the shape data of the irradiation line for one scan measured by the measurement device 50 (step S42). The specific method for setting the reflected wave extraction range is as described above.

[0057] Next, the control device 22 extracts, on the created B-scope, ultrasonic waves whose ultrasonic wave arrival times fall within the reflected wave extraction range as lower surface reflected waves (step S44).

[0058] Next, the control device 22 calculates the attenuation of the bottom-reflected wave for each transmission position based on the detected intensity of the bottom-reflected wave extracted in step S44 (step S45).

[0059] Then, control device 22 determines whether the attenuation of the bottom-reflected wave calculated in step S45 is greater than a threshold value (step S50). As described above, this threshold value is set to a value that allows the presence or absence of an internal defect to be distinguished for each transmission position. If it is determined that the attenuation of the bottom-reflected wave is greater than the threshold value (YES in step S50), control device 22 outputs a signal to display device 24 indicating that an internal defect has been detected in weld bead 6 (step S55).

[0060] As described above, the welding inspection device 1 according to this embodiment includes the measurement device 50 for measuring the external shape of the irradiation line on the base materials 2, 4 including the weld bead 6. The control device 22 sets the reflected wave extraction range based on the shape data of the irradiation line measured by the measurement device 50. This makes it possible to appropriately extract the bottom surface reflected wave even if the thickness or surface shape of the weld bead 6 changes.

[0061] Then, control device 22 determines the presence or absence of an internal defect in weld bead 6 based on the bottom surface reflected waves that have been appropriately extracted in this manner. Therefore, the presence or absence of an internal defect in weld bead 6 can be determined with high accuracy.

[0062] [Modification 1] In the above-described embodiment, the transmitting laser light emitting device 12 and the receiving laser light probe 18 are fixed to a robot that is movable in the Y direction, but a measuring device 50 may also be fixed to the robot.

[0063] Fig. 9 is a diagram schematically illustrating a portion of the exterior of welding inspection apparatus 1A according to Modification 1. As shown in Fig. 9, in welding inspection apparatus 1A, measuring device 50, transmitting laser light emitting device 12, and receiving laser light probe 18 are fixed to robot 110 that is movable in the Y direction.

[0064] In this way, the measurement device 50, the transmitting laser light emitting device 12, and the receiving laser light probe 18 may be fixed to one robot 110 that is movable in the Y direction. This makes it possible to measure the shape of the irradiation line and detect the reception intensity of the ultrasonic waves at the receiving point by a single operation of moving the robot 110 in the Y direction.

[0065] [Modification 2] In the above-described embodiment, the external shape of the irradiation line is measured by the measuring device 50 (laser scanner).

[0066] In contrast, in this variant example 2, attention is focused on the fact that ablation light is generated by irradiation with the transmitting laser light 14, and the three-dimensional position of the ablation light is calculated by photographing the ablation light generated by irradiation with the transmitting laser light 14 with a camera, and the shape data of the irradiation line is calculated by connecting the three-dimensional positions of the ablation light.

[0067] Ablation is a phenomenon in which a solid surface instantaneously becomes extremely hot and evaporates (vaporizes). Immediately after ablation occurs, atoms, molecules, ions, electrons, and other substances are explosively released from the solid surface, creating a type of plasma state that emits light. Ablation light is light (a type of plasma light) generated by ablation.

[0068] 10 is a diagram schematically illustrating a portion of the appearance of welding inspection device 1B according to modification 2. Welding inspection device 1B is obtained by removing measuring device 50 from welding inspection device 1 or welding inspection device 1A described above and adding stereo cameras 61 and 62.

[0069] The intensity of the transmission laser beam 14 is quite high, and at the irradiation position of the transmission laser beam 14, not only is an ultrasonic wave excited but ablation occurs, generating ablation light 60. This ablation light 60 is photographed by stereo cameras 61 and 62. The control device 22 calculates the three-dimensional position of the ablation light photographed by the stereo cameras 61 and 62 and calculates shape data of the irradiation line by connecting the calculated three-dimensional positions of the ablation light. The control device 22 then sets a reflected wave extraction range based on the shape data of the irradiation line calculated from the position of the ablation light, and determines the presence or absence of an internal defect in the weld bead 6 based on the bottom surface reflected wave extracted using the reflected wave extraction range. The method for setting the reflected wave extraction range is the same as the method described in the above embodiment.

[0070] In this way, the external shape data of the irradiation line may be calculated by using a stereo camera to capture images of the ablation light generated by irradiation with the transmission laser light 14. This makes it possible to measure the external shape data of the irradiation line without using the measuring device 50 (laser scanner).

[0071] Although Figure 10 shows an example in which the ablation light is photographed by stereo cameras 61 and 62, as long as the three-dimensional position of the ablation light can be calculated, the number of cameras photographing the ablation light is not necessarily limited to two (stereo) and may be one, or three or more.

[0072] [Modification 3] In the above-described modification 2, shape data of the irradiation line obtained by photographing the ablation light with at least one camera is used to inspect internal defects in the weld bead (setting the reflected wave extraction range).

[0073] In contrast to this, shape data of the irradiation line obtained by capturing an image of the ablation light with at least one camera may be used to inspect the appearance of the weld bead (detecting bead width, detecting pits, etc.) instead of or in addition to inspecting internal defects of the weld bead (setting the reflected wave extraction range). This allows the appearance inspection of the weld bead to be performed without using measurement device 50 (laser scanner).

[0074] [Variation 4] The configuration shown in Variation 2 in which the ablation light is captured by at least one camera can function as a shape measurement device by itself. Therefore, for example, the welding inspection function may be removed from welding inspection device 1B according to Variation 2 to form a shape measurement device. That is, a shape measurement device may be provided that includes an irradiation device that generates ablation light in a portion of the object irradiated with the laser light by scanning the object with pulsed laser light different from transmission laser light 14, and a measurement device that measures the external shape of the irradiated portion by capturing the ablation light with at least one camera.

[0075] Furthermore, an appearance inspection device may be provided that includes the shape measurement device described above and a control device that performs an appearance inspection of the portion irradiated with the laser light based on the measurement results from the shape measurement device.

[0076] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The technical scope of the present disclosure is defined by the claims, not by the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims.

[0077] 1, 1A, 1B Welding inspection device, 2, 4 Base material, 5 Lower surface, 6 Weld bead, 10 Transmitting laser source, 12 Transmitting laser light irradiation device, 14 Transmitting laser light, 16 Receiving laser source, 18 Receiving laser light probe, 20 Receiving laser light, 22 Control device, 24 Display device, 32 Transmitting point, 36 Receiving point, 40 Internal defect, 41 Non-passing component, 43 Passing component, 50 Measuring device, 52 Laser light, 60 Ablation light, 61, 62 Stereo camera, 110 Robot.

Claims

1. A welding inspection device for inspecting a welded portion included in an object, comprising: a first irradiation device that irradiates the welded portion with a transmitting laser beam and scans a transmission position, which is the irradiation position of the transmitting laser beam on the welded portion, in a first direction; a detection device that detects ultrasonic waves generated by the transmitting laser beam and reaching a receiving position on the object; a control device that extracts reflected waves reflected from the underside of the object from the ultrasonic waves detected by the detection device and determines whether or not there is an internal defect in the welded portion based on the extracted reflected waves; and a measurement device that measures the external shape of the portion of the object irradiated with the transmitting laser beam, wherein the control device sets reflected wave extraction conditions for extracting the reflected waves from the ultrasonic waves detected by the detection device based on the measurement results of the measurement device.

2. The welding inspection device according to claim 1, wherein the detection device includes a second irradiation device that irradiates the receiving position with a receiving laser light for detecting the reflected wave, and the control device sets, as the reflected wave extraction condition, an extraction time range that specifies for each transmission position the range of arrival time required for ultrasonic waves generated at the transmission position to be reflected by the underside of the object and reach the receiving position, and extracts ultrasonic waves that arrive within the extraction time range from among the ultrasonic waves detected by the detection device as the reflected wave.

3. The welding inspection device according to claim 2, wherein the control device shifts the extraction time range toward the side where the arrival time becomes longer as the propagation distance of the reflected wave estimated based on the measurement results by the measuring device becomes longer.

4. The welding inspection device according to claim 3, wherein the measuring device includes a laser scanner that measures the external shape of the irradiated portion by irradiating the irradiated portion with laser light.

5. The welding inspection device according to claim 4, wherein the laser scanner is fixed to a member to which the first irradiation device, the second irradiation device and the detection device are attached.

6. A welding inspection device according to any one of claims 1 to 3, wherein the first irradiation device generates ablation light at the irradiation portion by irradiating the irradiation portion with the transmission laser light, and the measurement device includes at least one camera that captures the ablation light generated at the irradiation portion.

7. A shape measurement device for measuring the external shape of an object, comprising: an irradiation device that irradiates the object with laser light and scans the laser light in a first direction to generate ablation light in a portion of the object irradiated with the laser light; and a measurement device that includes at least one camera that photographs the ablation light generated in the irradiated portion, and measures the external shape of the irradiated portion by photographing the ablation light with the at least one camera.

8. An appearance inspection device comprising: a shape measurement device according to claim 7; and a control device that performs an appearance inspection of the irradiated portion based on the measurement results obtained by the shape measurement device.

Images