Welding inspection method

Abstract

The welding inspection method includes: a step (S102) of removing impurities on a surface of a welded portion using a surface treatment device; a step (S110) for irradiating the surface of the welded part from which the impurities have been removed with a laser beam for transmission; a step (S120) for detecting the reflected ultrasonic waves reflected on the lower surface of the base material; and a step (S150) for determining the presence or absence of an internal defect in the welded portion on the basis of the detection result of the reflected ultrasonic waves.

Description

Technical Field

[0001] The invention relates to a welding inspection method. Background Art

[0002] For example, Patent Gazette No. 5651533 discloses a welding inspection method for nondestructively detecting internal defects such as pores generated in a weld. In this welding inspection method, a transmitting laser is irradiated from above the weld bead to the weld bead surface, and ultrasonic waves (scattered waves) reflected at the defects are detected to detect internal defects in the weld. Summary of the invention

[0003] In the welding inspection method disclosed in Japanese Patent No. 5651533, if impurities such as slag are present on the irradiation surface of the transmitting laser beam in the weld bead, the generation of ultrasonic waves is hindered, which may become a factor of inspection failure.

[0004] Therefore, an object of the present invention is to provide a welding inspection method capable of appropriately detecting internal defects of a weld portion even when foreign matter is attached to the surface of the weld portion.

[0005] (Item 1) The welding inspection method based on the present invention is a welding inspection method for inspecting a weld, wherein the welding inspection method includes: a step of removing impurities on the surface of the weld; a step of irradiating the surface of the weld after the impurities have been removed with a transmitting laser for exciting ultrasonic waves inside the inspection object; a step of detecting the ultrasonic waves excited by the transmitting laser; and a step of determining the presence or absence of internal defects in the weld based on the ultrasonic detection results.

[0006] According to this welding inspection method, impurities attached to the surface of the weld can be removed before irradiating the surface of the weld with the transmission laser. Therefore, even if impurities are attached to the surface of the weld, internal defects of the weld can be properly detected.

[0007] (Item 2) In the welding inspection method according to Item 1, the step of removing impurities includes the step of removing impurities by irradiating a surface of the weld portion with a transmission laser.

[0008] (Item 3) Based on the welding inspection method described in Item 1, the step of detecting ultrasonic waves includes the following steps: irradiating a receiving laser for detecting reflected ultrasonic waves to a specified position on the inspection object that can detect reflected ultrasonic waves reflected on the lower surface of the base material of the inspection object.

[0009] (Item 4) The welding inspection method described in Item 1 is performed during the processing while welding is being performed.

[0010] The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is an overall structural diagram of a welding system to which a welding inspection method is applied (part 1).

[0012] Figure 2 This is a diagram (part 1) for explaining the principle of detecting internal defects of a weld.

[0013] Figure 3 This is a diagram for explaining the principle of detecting internal defects of a weld portion (part 2).

[0014] Figure 4 This is a diagram showing the relationship between the irradiation position of the transmission laser light and the arrival time of the ultrasonic wave at the ultrasonic wave receiving point.

[0015] Figure 5 This is a diagram showing the relationship between the position of an ultrasonic wave transmission point and the intensity of an ultrasonic wave at an ultrasonic wave reception point.

[0016] Figure 6 This is a diagram for explaining a method for determining the presence or absence of internal defects in a weld.

[0017] Figure 7 This is a diagram showing a state where impurities (slag) are attached to the surface of the weld in a film form.

[0018] Figure 8 This is a flowchart (part 1) showing an example of a processing procedure of the control device.

[0019] Fig. 9 This is the overall structural diagram of the welding system to which the welding inspection method is applied (Part 2).

[0020] Fig.10 This is a flowchart (part 2) showing an example of the processing procedure of the control device. DETAILED DESCRIPTION

[0021] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the same reference numerals are given to the same or corresponding parts in the drawings, and their description will not be repeated.

[0022] Figure 11 is an overall structural diagram of a welding system 100 to which the welding inspection method according to the present embodiment is applied. The welding system 100 is used, for example, to inspect a weld (weld bead) 106 of a lap fillet weld of a thin plate (base materials 102, 104). The base materials 102, 104 are, for example, galvanized steel plates having a thickness of about 1 to 2 mm. It should be noted that in the figure, the Y direction indicates the welding advancing direction, the Z direction indicates the normal direction of the base materials 102, 104, and the X direction indicates a direction orthogonal to the Y direction and the Z direction.

[0023] The welding system 100 includes a robot arm 110 , a welding torch 112 , a cable 118 , a welding power source 120 , and a controller 122 .

[0024] The robot arm 110 is a multi-jointed arm, for example, a six-axis multi-jointed arm. The robot arm 110 is controlled by a controller 122 so as to weld the base materials 102 and 104 at a set welding speed using a welding torch 112 .

[0025] The welding torch 112 supplies welding wire and shielding gas (argon or carbon dioxide, etc.) toward the joint of the base materials 102 and 104. The welding torch 112 receives welding current from the welding power source 120 through the cable 118, and generates an arc 1114 between the tip of the welding wire and the joint of the base materials 102 and 104.

[0026] It should be noted that, instead of welding wire, a filler (filler metal) for forming weld metal may be added and an electrode (tungsten, etc.) of a non-consumable material may be used. That is, arc welding performed by the welding torch 112 may be either a melting electrode type (MAG welding, MIG welding, etc.) using welding wire or a non-melting electrode type (TIG welding, etc.) accompanied by the addition of a filler.

[0027] Welding power source 120 generates a welding voltage and a welding current for arc welding, and outputs the generated welding voltage and welding current to welding torch 112 .

[0028] The controller 122 is composed of a CPU (Central Processing Unit), a memory (RAM (Random Access Memory) and ROM (Read Only Memory)), and an input / output port (not shown) for inputting and outputting various signals. The CPU expands the program stored in the ROM to the RAM and executes it. The various processes executed by the controller 122 are described in the program stored in the ROM.

[0029] The controller 122 controls the operation of the robot 110 and the output of the welding power source 120 so that the welding torch 112 welds the base materials 102 and 104 at a set welding speed. At this time, the controller 122 controls the robot 110 so that the welding inspection head 130 (described later) is located behind the welding torch 112 in the welding travel direction.

[0030] In addition, the controller 122 cooperates with the control device 164 that controls the welding inspection head 130, and exchanges various signals with the control device 164. For example, the controller 122 notifies the control device 164 of the start, stop, continuation, and welding speed of welding performed by the welding torch 112. In addition, when the controller 122 receives a defect detection signal indicating that an internal defect of the welded portion is detected from the control device 164, it can stop the welding performed by the welding torch 112 or change the welding conditions.

[0031] The welding system 100 further includes a welding inspection head 130 , optical fibers 142 , 148 , a link 150 , a transmitting laser source 160 , a receiving laser source 162 , and a control device 164 .

[0032] The welding inspection head 130 includes a transmitting laser irradiation device 134 and a receiving laser probe 144. The transmitting laser irradiation device 134 and the receiving laser probe 144 are mounted on a mounting member 132. The mounting member 132 is connected to the robot arm 110 via a link 150.

[0033] Transmitting laser irradiation device 134 includes microchip laser 136, scanning mechanism 138, and photodetector 140. Microchip laser 136 is a small solid laser using, for example, YAG crystal, and receives excitation light from transmitting laser source 160 via optical fiber 142 to generate high-output pulsed laser light.

[0034] The scanning mechanism 138 includes a mechanism for scanning the irradiation position of the pulse laser generated by the microchip laser 136 in the welding direction (Y direction) and the welding width direction (X direction). The scanning mechanism 138 is configured to include, for example, a galvanometer mirror capable of adjusting an angle and a driving mechanism for driving the galvanometer mirror. During the welding inspection, the driving mechanism of the scanning mechanism 138 is controlled by the control device 164 so that the ultrasonic transmission point group 154 ​​irradiated with the transmission laser 152 (pulse laser) includes the entire area of ​​the width direction (X direction) of the weld bead 106.

[0035] The photodetector 140 detects the oscillation of the transmission laser light 152 (pulse laser light), and outputs a trigger signal Tr to the control device 164 every time the pulse laser light oscillates.

[0036] The receiving laser probe 144 irradiates the receiving laser 156 (reference light) received from the receiving laser source 162 through the optical fiber 148 to a predetermined position in the X direction on the base material 104, that is, an ultrasonic receiving point 158. In addition, the receiving laser probe 144 receives the reflected light of the receiving laser 156 irradiated to the base material 104, which is reflected from the base material 104, and outputs it to the receiving laser source 162 through the optical fiber 148.

[0037] The receiving laser source 162 is configured to include a laser interferometer, and outputs the receiving laser 156 (reference light) irradiated to the base material 104 to the receiving laser detector 144 through the optical fiber 148. In addition, the receiving laser source 162 receives the reflected light of the receiving laser 156 reflected from the base material 104 received by the receiving laser detector 144 from the receiving laser detector 144, and outputs a detection signal IS of interference light including the reference light and reflected light of the receiving laser 156 to the control device 164.

[0038] It should be noted that the irradiation positions of the transmitting laser 152 and the receiving laser 156 are preferably close to the welding position (molten pool 116 ) in consideration of defect detection during welding processing, and can be set, for example, 20 to 30 mm behind the molten pool 116 in the welding advancing direction.

[0039] Similar to the controller 122, the control device 164 is configured to include a CPU, a memory (RAM and ROM), and an input / output port (not shown) for inputting and outputting various signals. The CPU expands and executes the program stored in the ROM in the RAM. The various processes performed by the control device 164 are described in the program stored in the ROM.

[0040] The control device 164 measures the detection signal IS of interference light between the reference light and the reflected light of the receiving laser 156 for a predetermined time (e.g., 10 μs) based on the trigger signal Tr from the photodetector 140 indicating the timing of oscillation of the transmission laser 152 (pulse laser). In addition, the control device 164 measures the intensity of the ultrasonic wave at the ultrasonic wave receiving point 158 ​​corresponding to the trigger signal Tr based on the measured detection signal IS of interference light.

[0041] The control device 164 performs the above-mentioned ultrasonic intensity measurement at the ultrasonic receiving point 158 ​​while scanning the irradiation position (ultrasonic transmission point) of the transmission laser 152 along the width direction (X direction) of the weld 106. And, when the measurement corresponding to one scan is completed, the control device 164 determines whether an internal defect occurs in the weld 106 based on the attenuation of the ultrasonic wave (reflected ultrasonic wave) reflected from the lower surface of the lower plate (base material 104) and reaching the ultrasonic receiving point 158.

[0042] In the welding system 100, the laser ultrasonic method is used to detect internal defects of the weld 106. That is, the weld 106 of the inspection object is irradiated with the transmitting laser 152 to generate ultrasonic waves inside the inspection object, and the surface vibration corresponding to the intensity of the ultrasonic wave at the ultrasonic wave receiving point 158 ​​irradiated with the receiving laser 156 is detected by the interference light of the reference light and the reflected light of the receiving laser 156. And the presence or absence of the internal defect of the weld 106 is determined based on the detection difference between the case where the weld 106 does not have an internal defect and the case where the internal defect exists.

[0043] Figure 2 as well as Figure 3 This is a diagram for explaining the principle of detecting internal defects of a welded portion by welding system 100 . Figure 2 shows the state when there is no defect in the weld 106, Figure 3 The figure shows a state in which internal defects (pores, etc.) occur in the welded portion 106 .

[0044] Reference Figure 2 In the welding system 100, a transmitting laser 152 is irradiated from above (in the Z direction) to a region including a welded portion 106, and ultrasonic waves are excited at the irradiation position of the laser. The generated ultrasonic waves pass through the welded portion 106, are reflected by the lower surface 105 of the base material 104 at the lower side, and then reach the upper surface of the base material 104. The minute vibrations generated on the surface of the base material 104 by the arrived ultrasonic waves are measured using a receiving laser 156 (interferometry using a laser interferometer), thereby measuring the intensity of the ultrasonic waves at the irradiation position of the receiving laser 156 (ultrasonic wave receiving point 158).

[0045] The irradiation position of the transmission laser 152 is scanned in the X direction using the scanning mechanism 138. The ultrasonic transmission point group 154 ​​indicated by the × mark indicates the irradiation position of the transmission laser 152 which is a pulse laser. After the measurement at a certain irradiation position is completed, the irradiation position of the transmission laser 152 is scanned to the next position, and the measurement at the irradiation position is performed.

[0046] The irradiation position of the receiving laser 156 is fixed in the X direction of the base material 104. The ultrasonic receiving point 158 ​​indicated by the circle indicates the irradiation position of the receiving laser 156. The larger the distance in the X direction between each ultrasonic transmission point group 154 ​​and the ultrasonic receiving point 158, the longer the propagation time of the ultrasonic wave from each ultrasonic transmission point group 154 ​​to the ultrasonic receiving point 158, and the intensity of the ultrasonic wave at the ultrasonic receiving point 158 ​​(micro vibration of the surface) also decreases due to diffusion attenuation.

[0047] Reference Figure 3When there is a defect 107 such as a pore in the weld 106, in addition to diffusion attenuation, scattering attenuation occurs at the defect 107, so the intensity of the ultrasonic wave 155 reaching the ultrasonic wave receiving point 158 ​​becomes smaller (attenuation becomes larger) than when there is no defect 107. Therefore, by capturing the attenuation of the ultrasonic wave reaching the ultrasonic wave receiving point 158, the presence or absence of the defect 107 in the weld 106 can be determined.

[0048] Figure 4 1 is a diagram showing the relationship between the irradiation position of the transmission laser 152 and the arrival time of the ultrasonic wave at the ultrasonic wave receiving point 158. Figure 4 In the figure, the horizontal axis represents the irradiation position of the transmission laser 152 in the X direction (the position of the ultrasonic transmission point), and the larger the value, the farther from the ultrasonic reception point 158. The vertical axis represents the time from the irradiation of the transmission laser 152 (from the generation of ultrasonic waves at the ultrasonic transmission point) to the arrival of the ultrasonic wave at the ultrasonic reception point 158.

[0049] exist Figure 4 In FIG. 1 , line L1 indicates the arrival time of the ultrasonic wave (surface wave) transmitted through the weld 106 and the surface of the base material 104. Line L2 indicates the arrival time of the ultrasonic wave (reflected wave) transmitted from the ultrasonic transmission point through the weld 106 and reflected on the lower surface 105 of the base material 104.

[0050] The arrival time of the above-mentioned surface wave is not affected by the presence or absence of the defect 107. Therefore, based on the relationship between the position of the ultrasonic transmitting point and the arrival time, it is possible to distinguish whether the ultrasonic wave detected at the ultrasonic receiving point is a surface wave or an ultrasonic wave (reflected wave) reflected on the lower surface 105 of the base material 104.

[0051] Figure 5 is a diagram showing the relationship between the position of the ultrasonic transmission point and the intensity of the ultrasonic wave at the ultrasonic reception point. Figure 5 In, with Figure 4 Similarly, the horizontal axis represents the position of the ultrasonic transmission point. The vertical axis represents the position of the ultrasonic reception point. Figure 4 The intensity of the reflected wave (line L2).

[0052] exist Figure 5 In the figure, line L3 represents the reflected wave at the ultrasonic receiving point when there is no internal defect in the welded portion 106 ( Figure 4 The greater the value of the position of the ultrasonic transmission point (the farther from the ultrasonic reception point), the more the signal strength decays due to diffusion attenuation.

[0053] Line L4 represents the reflected wave ( Figure 4If the position of the ultrasonic transmission point is at a Figure 5 If the position Z1 shown is large, the reflected wave reaching the ultrasonic receiving point passes through the internal defect generated in the welded portion 106. At this time, in addition to the diffusion attenuation, the scattering attenuation caused by the internal defect also occurs, so the reflected wave intensity at the ultrasonic receiving point (line L4) is smaller than the reflected wave intensity (line L3) when there is no internal defect. That is, at the ultrasonic receiving point, the attenuation of the reflected wave when the internal defect occurs becomes larger than when there is no internal defect.

[0054] Figure 6 1 is a diagram for explaining a method for determining the presence or absence of an internal defect in the weld 106. The presence or absence of an internal defect in the weld 106 is determined by the magnitude of the attenuation corresponding to the position of the ultrasonic transmission point with respect to the intensity of the reflected wave at the ultrasonic reception point. That is, if the attenuation corresponding to the position of the ultrasonic transmission point is less than a predetermined threshold value, it is determined that there is no internal defect, and if the attenuation is greater than the threshold value, it is determined that an internal defect has occurred in the weld 106 to be inspected. It should be noted that the threshold value is appropriately set to a value capable of distinguishing the presence or absence of an internal defect through a prior evaluation test or the like.

[0055] <Impurities removal from the surface of welded part>

[0056] Impurities such as slag generated during welding may adhere to the surface of the welded portion 106. Slag is a product of oxides of silicon (Si), manganese (Mn), iron (Fe), etc. exposed on the surface of the welded portion.

[0057] Figure 7 This is a diagram showing a state where impurities (slag) 108 are attached to the surface of the weld 106 in a film-like state. When the impurities 108 are attached to the surface of the weld 106, the transmission laser is irradiated to the impurities 108 during the welding inspection, which may hinder the generation of ultrasonic waves. As a result, this may become a major cause of poor welding inspection.

[0058] Therefore, the welding system 100 according to this embodiment is as follows Figure 1 As shown in the figure, a surface treatment device 200 is also provided. The surface treatment device 200 is a tool for removing impurities 108 attached to the surface of the welded portion 106. The surface treatment device 200 is connected to the welding inspection head 130. Figure 1 In the illustrated example, the surface treatment device 200 is connected to the welding inspection head 130 via a link 210 .

[0059] The surface treatment device 200 according to the present embodiment has a removal mechanism (brush, etc.) that contacts the surface of the weld 106 and mechanically removes the surface of the weld 106, and uses the removal mechanism to remove the impurities 108 attached to the surface of the weld 106. It should be noted that the method of removing impurities is not limited to the method of mechanically removing the surface of the weld 106. For example, the surface treatment device 200 may be configured using a laser irradiation device whose output is adjusted to remove the impurities 108 attached to the surface of the weld 106. In this case, by irradiating the surface of the weld 106 with laser light from the surface treatment device 200, the impurities 108 attached to the surface of the weld 106 can be removed in a non-contact manner using the impact generated by the ablation of the laser.

[0060] The control device 164 performs the following first to fourth steps in sequence when performing welding inspection.

[0061] (First Step) Impurities on the surface of the welded portion 106 are removed using the surface treatment device 200 .

[0062] (Second step) The surface of the welded portion 106 from which impurities have been removed is irradiated with a transmitting laser.

[0063] (Third Step) The ultrasonic wave (reflected wave) reflected by the lower surface 105 of the base material 104 is detected.

[0064] (Fourth Step) The presence or absence of internal defects in the welded portion 106 is determined based on the detection result of the reflected wave.

[0065] It should be noted that the position of the surface treatment device 200 according to this embodiment is pre-adjusted as follows: Figure 1 As shown, the removal position processed by the surface treatment device 200 is located behind the molten pool 116 (the welding position of the welding torch 112) in the welding advancing direction and in front of the ultrasonic transmission point group 154 ​​(the irradiation position of the transmission laser 152) in the welding advancing direction. Therefore, when welding inspection is performed during processing during welding, impurities on the surface of the welded portion 106 can be removed in advance by the surface treatment device 200 before the transmission laser 152 is irradiated to the surface of the welded portion 106.

[0066] Figure 8 This is a flowchart showing an example of a processing procedure when the control device 164 according to the present embodiment performs a welding inspection during welding.

[0067] The control device 164 operates the surface treatment device 200 to remove impurities on the surface of the welded portion 106 (step S102). It should be noted that when the welding inspection head 130 also moves in the welding advancing direction (Y direction) together with the welding torch 112 during welding, the surface treatment device 200 is connected to the welding inspection head 130, and the removal position processed by the surface treatment device 200 is adjusted to be located behind the molten pool 116 in the welding advancing direction and in front of the ultrasonic transmission point group 154 ​​in the welding advancing direction as described above. Therefore, the position irradiated with the transmission laser 152 in the subsequent steps is in a state where impurities have been removed. It should be noted that the processing of step S102 corresponds to the above-mentioned "first process".

[0068] Next, the control device 164 controls the scanning mechanism 138 to irradiate the transmission laser 152 to a predetermined position in the X direction of the welded portion 106 (step S110). The positions in the X direction of each irradiation point of the transmission laser 152 in one scan are preset, and a predetermined number (e.g., 20) of irradiation positions are set in the region including the welded portion 106. It should be noted that the processing of step S110 corresponds to the above-mentioned "second process".

[0069] Next, the oscillation (irradiation) of the transmission laser 152 (pulse laser) is detected by the photodetector 140, and a trigger signal Tr indicating the start of ultrasonic wave detection corresponding to the pulse irradiation is transmitted from the photodetector 140 to the control device 164 (step S115).

[0070] The control device 164 measures the intensity of the ultrasonic wave at the ultrasonic receiving point 158 ​​obtained based on the interference light of the receiving laser 156 obtained by the laser interferometer for a predetermined time (e.g., 10 μs) based on the trigger signal Tr (step S120). It should be noted that the processing of steps S115 and S120 corresponds to the above-mentioned "third step".

[0071] Next, the control device 164 determines whether the transmission laser 152 has completed the measurement corresponding to one scan (step S125). Specifically, it determines whether the measurement has been completed at all the irradiation positions preset in the X direction. If the measurement corresponding to one scan has not been completed (No in step S125), the control device 164 updates the irradiation position of the transmission laser 152 to the next position (step S130). Then, the process returns to step S110.

[0072] When it is determined in step S125 that the measurement corresponding to one scan of the transmitting laser 152 is completed (Yes in step S125), the control device 164 determines whether there is an internal defect in the welding portion 106 corresponding to one scan based on the measurement result corresponding to one scan (step S150).

[0073] Specifically, the control device 164 extracts the signal of the reflected wave (ultrasonic wave reflected on the lower surface of the base material 104 and reaching the ultrasonic wave receiving point 158) at the irradiation position (ultrasonic wave transmitting point) of the receiving laser 156 for each irradiation position (ultrasonic wave transmitting point) of the transmitting laser 152 scanned in the X direction based on the measurement result corresponding to one scan. And, the control device 164 calculates the attenuation of the ultrasonic wave corresponding to the irradiation position (transmission position) of the transmitting laser 152 for the extracted reflected wave signal, and determines whether the calculated attenuation is greater than a threshold value. The threshold value is appropriately set to a value capable of distinguishing the presence or absence of internal defects through a prior evaluation test. And, when the attenuation is greater than the threshold value, the control device 164 determines that there is an internal defect in the weld bead 106 corresponding to one scan. It should be noted that the processing of step S150 corresponds to the above-mentioned "fourth process".

[0074] If it is determined in step S150 that an internal defect exists (YES in step S150 ), the control device 164 outputs a defect detection signal indicating that a defect is detected in the welded portion 106 to the controller 122 on the robot side (step S152 ). Then, the control device 164 moves the process to step S160 .

[0075] On the other hand, when it is determined in step S150 that there is no internal defect (NO in step S150), the control device 164 does not execute the process of step S152 and moves the process to step S160.

[0076] Next, the control device 164 determines whether to continue welding based on the signal from the controller 122 indicating whether welding needs to be continued (step S160). Then, when welding is continued (yes in step S160), the control device 164 moves to the measurement at the next measurement line (step S165), and returns the process to step S110.

[0077] On the other hand, when it is determined in step S160 that welding is to be stopped based on the signal from controller 122 (NO in step S160), control device 164 ends the welding inspection process.

[0078] As described above, the welding inspection method based on the present embodiment includes: a step of removing impurities from the surface of the weld 106 using the surface treatment device 200 (a first step); a step of irradiating the surface of the weld 106 from which the impurities have been removed with a transmitting laser (a second step); a step of detecting reflected ultrasonic waves reflected from the lower surface 105 of the base material 104 (a third step); and a step of determining the presence or absence of internal defects in the weld 106 based on the detection result of the reflected ultrasonic waves (a fourth step).

[0079] According to such a welding inspection method, even if impurities generated during welding are attached to the surface of the weld 106, the impurities can be removed before irradiating the surface of the weld 106 with the transmission laser. Therefore, even if impurities generated during welding are attached to the surface of the weld 106, internal defects of the weld 106 can be appropriately detected.

[0080] [Modification 1]

[0081] In the above embodiment, an example is described in which a dedicated surface treatment device 200 is provided for removing impurities 108 attached to the surface of the weld 106. However, the impurities 108 attached to the surface of the weld 106 may be removed using a transmitting laser without providing a dedicated surface treatment device 200.

[0082] Fig. 9 1 is an overall configuration diagram of a welding system 100A to which the welding inspection method according to Modification 2 is applied. The welding system 100A is obtained by removing the surface treatment device 200 and the link 210 from the above-mentioned welding system 100 .

[0083] In the welding system 100A, since the scanning mechanism 138 (galvanometer mirror, etc.) for scanning the transmission laser is provided in the transmission laser irradiation device 134, the scanning mechanism 138 is controlled so as to irradiate the surface of the weld 106 with the transmission laser 152a to remove impurities attached to the surface of the weld 106, and the scanning mechanism 138 is controlled so as to irradiate the surface of the weld 106 with the transmission laser 152 after the impurities are removed. Thus, the transmission laser can be used for impurity removal. As a result, internal defects of the weld 106 can be appropriately detected without providing a dedicated surface treatment device 200.

[0084] Fig.10 1 is a flowchart showing an example of a processing procedure when the control device 164 according to the present modification example 1 performs a welding inspection during welding. Fig.10 The flowchart is obtained by combining the above Figure 8 Step S102 is changed to step S102A.

[0085] First, the control device 164 controls the scanning mechanism 138 to irradiate the surface of the weld portion 106 corresponding to the next scheduled scan with the transmission laser 152a, thereby removing impurities attached to the surface corresponding to the next scheduled scan (step S102A).

[0086] Next, the control device 164 irradiates the surface corresponding to one scan with the transmission laser beam 152 to perform welding inspection (steps S110 to S152 ).

[0087] If welding is continued (Yes in step S160), the control device 164 moves to the measurement at the next measurement line (step S165), and returns the process to step S102A. If welding is stopped (No in step S160), the control device 164 ends the welding inspection process.

[0088] As described above, the impurities 108 adhering to the surface of the welded portion 106 may be removed by irradiating the surface of the welded portion 106 with the transmission laser beam 152 .

[0089] [Modification 2]

[0090] In the welding inspection method according to the above-described embodiment, whether or not the impurities 108 are attached to the surface of the welded portion 106 is not verified, and the impurity removal by the surface treatment device 200 is always performed.

[0091] On the other hand, after verifying in advance whether or not the impurities 108 are attached to the surface of the weld 106, the impurity removal by the surface treatment device 200 may be performed only when the verification result that the impurities 108 are attached is obtained. Specifically, for example, first, the first welding inspection is performed without performing the impurity removal by the surface treatment device 200, and it is estimated whether or not the impurities are attached to the surface of the weld 106 based on the result of the first welding inspection. And, if it is estimated that the impurities are not attached based on the result of the first welding inspection, the welding inspection is terminated. On the other hand, if it is estimated that the impurities are attached based on the result of the first welding inspection, the impurity removal by the surface treatment device 200 is performed and the second welding inspection is performed. By such a modification, it is easy to avoid performing the impurity removal by the surface treatment device 200 even when the impurities 108 are not attached to the surface of the weld 106. As a result, the welding inspection can be performed efficiently.

[0092] [Variation 3]

[0093] In the welding inspection method based on the above-mentioned embodiment, the receiving laser is irradiated from the receiving laser detector 144 to the ultrasonic receiving point 158 ​​and the reflected wave is detected in a non-contact manner, but the method of detecting the reflected wave is not limited to the non-contact method. For example, a device (contact piece) that contacts the ultrasonic receiving point 158 ​​and detects the reflected wave of the ultrasonic receiving point 158 ​​may be arranged, and the reflected wave may be detected by using the device.

[0094] [Variation 4]

[0095] In the welding inspection method based on the above-mentioned embodiment, the ultrasonic wave (reflected wave) excited by the transmitting laser and reflected on the lower surface 105 of the base material 104 is detected, but the ultrasonic wave that becomes the detection object only needs to be the ultrasonic wave excited by the transmitting laser, and does not need to be limited to the ultrasonic wave reflected on the lower surface 105 of the base material 104.

[0096] [Variation 5]

[0097] In the welding system 100 according to the above embodiment, the surface treatment device 200 is connected to the welding inspection head 130, but the surface treatment device 200 is not limited to being connected to the welding inspection head 130. That is, the welding inspection head 130 and the surface treatment device 200 may be mounted on different robots.

[0098] The above-mentioned embodiment and the solutions shown in Modifications 1 to 5 thereof can be appropriately combined within a range where no technical contradiction occurs.

[0099] The embodiments of the present invention have been described, but all points of the embodiments disclosed this time are illustrative and not restrictive. The scope of the present invention is indicated by the technical claims, and is intended to include all changes within the meaning and scope equivalent to the technical claims.

Claims

1. A welding inspection method, which is a welding inspection method for inspecting a welded portion, wherein: The welding inspection method comprises: The step of removing impurities from the surface of the welding portion; a step of irradiating the surface of the welded portion from which impurities have been removed with a transmitting laser for exciting ultrasonic waves inside the inspection object; a step of detecting the ultrasonic wave excited by the transmitting laser; and The step of determining the presence or absence of internal defects in the welded portion based on the ultrasonic detection result.

2. The welding inspection method according to claim 1, wherein: The step of removing the impurities includes the step of removing the impurities by irradiating the surface of the weld portion with the transmission laser.

3. The welding inspection method according to claim 1, wherein: The step of detecting the ultrasonic wave includes the step of irradiating a receiving laser beam for detecting the reflected ultrasonic wave to a predetermined position on the inspection object where reflected ultrasonic wave reflected on the lower surface of a base material of the inspection object can be detected.

4. The welding inspection method according to claim 1, wherein: The welding inspection method is performed during the execution of welding during processing.

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