Welding Systems

Abstract

To provide a welding system which can detect defects of welding during welding work.SOLUTION: A welding system according to the invention controls a welding robot 20 which performs welding to a steel material while moving on the steel material in a predetermined direction Y1. The welding system includes: imaging means 30 which captures images of a molten pool of the steel material to be welded by the welding robot 20; measuring means which measures a length of the molten pool or a width of the molten pool based on image data formed by the imaging means 30 capturing the images of the molten pool and outputting the images; and output means which outputs defect information regarding defects of welding by the welding robot 20 based on the length or the width measured by the measuring means.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a welding system. [Background technology]

[0002] When welding steel materials, a molten pool is generated between the ends of the steel materials (groove). If this molten pool falls off before it hardens, a welding defect occurs. To address this issue, the following technology has been disclosed. Patent Document 1 discloses an automatic welding system that uses a camera to capture images of the arc and molten pool from the front in the direction of welding progress, detects the tip of the molten pool using a pre-trained machine learning model, and determines the amount of correction to the welding speed based on the distance between the detected position and the arc if the distance is within a specified range. Patent Document 2 discloses a welding system in which an image of a weld bead is acquired by an image acquisition unit, a calculation unit calculates the variation in brightness values ​​of the image, and a judgment unit judges the presence or absence of a defect in a portion corresponding to a certain area on the weld bead based on the calculated variation in brightness values. Patent Document 3 discloses a welding system in which a controller acquires welding-related information from a welding device during welding and determines welding abnormalities using a trained model held in the controller. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-79444 [Patent Document 2] JP 2017-148841 A [Patent Document 3] JP 2019-188435 A Summary of the Invention [Problem to be solved by the invention]

[0004] The technology described in Patent Document 1 determines the shape of the molten pool and the position of the leading edge of the molten pool using a machine learning model. Therefore, if the positional relationship between the camera, the arc, and the molten pool changes during welding work, there is a problem that the shape of the molten pool cannot be detected accurately. The technology described in Patent Document 2 is a method for capturing an image of the weld bead after it has melted and solidified, and making judgments. Therefore, it is not possible to detect welding defects that occur in a molten state, such as dripping of the molten pool. In the technology described in Patent Document 3, the current and voltage waveforms of the arc are reflected as information on the welding status. However, even if the shape of the rear end of the molten pool changes, if there is a distance from the arc, it does not affect the current and voltage waveform. Therefore, it is difficult for the system according to this invention to detect dripping of the molten pool.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a welding system capable of detecting welding defects during welding work. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention proposes the following means. The welding system of the present invention is a welding system that controls a welding robot that moves in a predetermined direction over steel material while welding the steel material, and is equipped with an imaging means that images a molten pool of the steel material being welded by the welding robot, a measuring means that measures the length or width of the molten pool based on image data output by the imaging means after imaging the molten pool, and an output means that outputs defect information regarding defects in welding by the welding robot based on the length or width measured by the measuring means.

[0007] According to this invention, the imaging means images the molten pool and outputs the image data. The measuring means measures the length or width of the molten pool based on the output image data. The output means outputs defect information related to defects in welding by the welding robot based on the measured length or width of the molten pool. Here, if the molten pool drips before hardening during welding operation, the length or width of the molten pool will rapidly decrease. Alternatively, if the molten pool at the welded portion is not continuous but is interrupted midway, there will be a portion where the molten pool is not formed. By providing the above-mentioned configuration to address these events, it is possible to quickly detect, during welding operation, that the molten pool has dripped or been interrupted before hardening. This contributes to higher welding quality.

[0008] The imaging means may include an opposite side camera provided on a side of the welding robot opposite to the side in the predetermined direction.

[0009] According to this invention, the imaging means includes an opposite side camera provided on a side of the welding robot opposite to the predetermined direction in which the welding robot advances. In other words, the opposite side camera is attached to the side of the welding robot and images the molten pool from the opposite side of the direction of advancement. This makes it possible to image the area where the welding robot has welded and where the molten pool has formed, tracking the movement of the welding robot. This makes it easier to grasp the width and length of the molten pool more accurately.

[0010] The welding robot may further include a welding torch, and the imaging means may image the molten pool from a position relative to the welding torch and on the opposite side to the specified direction.

[0011] According to this invention, the imaging means images the molten pool from a position relative to the welding torch and opposite to the predetermined direction in which the welding robot advances. This allows the molten pool to be imaged immediately after it is generated, thereby making it possible to more accurately image the molten pool before hardening begins.

[0012] The system may further include a construction jig attached to the steel material, an acquisition means for acquiring construction jig position information indicating the position of the construction jig, and a memory control means, wherein the imaging means includes an opposite side camera attached to a side of the welding robot opposite the side in the specified direction, and the memory control means stores in a memory unit as a log the position of the welding robot where the molten pool cannot be imaged by the opposite side camera based on the position information of the construction jig acquired by the acquisition means.

[0013] According to this invention, the memory control means stores in the memory unit as a log the position of the welding robot where the molten pool cannot be imaged by the opposite camera, based on the position information of the construction jig acquired by the acquisition means. Here, when the welding robot welds near the construction jig attached to the steel material, the construction jig may interfere with the field of view of the imaging means, making it impossible to image the state of the molten pool. In response to this, by storing the position where the molten pool cannot be imaged as a log in the memory unit, the position can be easily confirmed after the welding work. Therefore, the confirmation work after welding can be performed efficiently.

[0014] The imaging means may further include an opposite side camera provided on a side of the welding robot opposite the side facing the predetermined direction, and a predetermined direction camera provided on a side of the welding robot facing the side facing the predetermined direction, and the measuring means may measure the length or width based on image data output by the opposite side camera after imaging the molten pool, and may measure the width based on image data output by the predetermined direction camera after imaging the molten pool.

[0015] According to this invention, the measuring means measures the length or width based on image data output by the opposite side camera after capturing an image of the molten pool, and measures the width based on image data output by the predetermined direction side camera after capturing an image of the molten pool. As a result, even if the opposite side camera cannot capture an image of the molten pool due to, for example, an interference of a construction jig with the field of view of the opposite side camera, at least the width of the molten pool can be captured by the predetermined direction side camera. In this way, by providing the predetermined direction side camera having an auxiliary role in the imaging means, imaging can be performed more stably. Furthermore, by providing cameras on both the predetermined direction side and the opposite direction side, at least the width of the molten pool can be measured by either camera when the traveling direction of the welding robot changes. Alternatively, the predetermined direction side camera and the opposite side camera can switch roles. As a result, imaging can be performed more stably.

[0016] The welding robot may further include a detection means, wherein the imaging means includes an opposite side camera provided on a side of the welding robot opposite the side facing the predetermined direction, and a predetermined direction camera provided on a side of the welding robot facing the predetermined direction, and the measurement means measures the length or width based on image data output by the opposite side camera after imaging the molten pool, and the detection means detects burn-through of welding by the welding robot based on image data output by the predetermined direction camera after imaging the molten pool.

[0017] According to this invention, the measuring means measures the length or width of the molten pool based on image data output by the opposite-side camera after capturing an image of the molten pool. In addition, the detecting means detects burn-through in welding by the welding robot based on image data output by the predetermined-direction camera after capturing an image of the molten pool. In this way, by simultaneously measuring the length or width of the molten pool with the measuring means and detecting burn-through with the detecting means, it is possible to more reliably detect welding defects.

[0018] The welding robot may further include a welding torch and a control means, wherein the imaging means includes an opposite side camera provided on a side of the welding robot opposite the predetermined direction side, and a predetermined direction side camera provided on a side of the welding robot opposite the predetermined direction side, and the control means controls the opposite side camera to image the molten pool from a position relative to the welding torch opposite the predetermined direction when the welding robot moves in the predetermined direction, and controls the predetermined direction side camera to image the molten pool from a position relative to the welding torch on the predetermined direction side when the welding robot flips over and moves in the opposite direction to the predetermined direction.

[0019] According to this invention, when the welding robot moves in the predetermined direction, the control means controls the opposite side camera to capture an image of the molten pool from a position relative to the welding torch that is opposite to the predetermined direction, and when the welding robot turns around and moves in the opposite direction to the predetermined direction, the control means controls the predetermined direction side camera to capture an image of the molten pool from a position relative to the welding torch on the side of the predetermined direction. This allows the imaging means to continue capturing an image of the molten pool regardless of which side the welding robot moves to.

[0020] In addition, the defect information may include symptom information regarding a symptom of the defect, and the symptom information may be output by the output means based on the value of the length or width measured by the measurement means.

[0021] According to this invention, the defect information includes symptom information on a symptom of a defect, and the symptom information is output by the output means based on the length or width value measured by the measuring means. In this way, by outputting the symptom information on the symptom of a defect by the output means in addition to the welding defect information, it is possible to detect the occurrence of a welding defect before it occurs and to respond quickly. Therefore, the quality of the welding can be further improved.

[0022] The welding robot may further include a change means for changing a state of the welding robot based on the symptom information output by the output means.

[0023] According to the present invention, the welding robot may further include a change means for changing a state of the welding robot based on the symptom information output by the output means. In this manner, by appropriately changing the state of the welding robot in response to the symptom of a welding defect, it is possible to prevent the occurrence of a welding defect.

[0024] The state may also be characterized in that it includes a speed at which the welding robot moves in the specified direction, an inclination angle of a welding torch held by the welding robot relative to the specified direction, a speed at which the welding robot feeds wire, and a distance between a groove formed in the steel material and the tip of the welding torch held by the welding robot.

[0025] According to this invention, the state of the welding robot changed by the change means includes the speed at which the welding robot moves in a predetermined direction, the inclination angle of the welding torch held by the welding robot relative to the predetermined direction, the speed at which the welding robot feeds the wire, and the distance between the groove formed in the steel material and the tip of the welding torch held by the welding robot.

[0026] By changing the movement speed of the welding robot, the time that the welding torch stays at any position in the weld can be adjusted. By changing the tilt angle of the welding torch, the effect on the shape of the molten pool after welding can be adjusted. By changing the speed at which the wire is fed, the amount of material that becomes the molten pool after welding can be adjusted. By changing the distance between the groove and the tip of the welding torch, the temperature of the weld can be adjusted. In this way, by appropriately changing the welding robot using the changing means, the possibility of welding defects occurring can be minimized.

[0027] Moreover, the defect information may include occurrence information regarding the occurrence of the defect, and the occurrence information may be output by the output means based on a change in the length or width measured by the measuring means exceeding a predetermined threshold value.

[0028] According to the present invention, the defect information includes occurrence information regarding the occurrence of a defect, and the occurrence information is output by the output means based on the fact that a change in the length or width of the molten pool measured by the measuring means exceeds a predetermined threshold. In this way, the occurrence of a welding defect can be detected by outputting the information that a welding defect has occurred by the output means.

[0029] The welding robot may further include a stop means for stopping the welding robot based on the generated information output by the output means.

[0030] According to this invention, the welding robot is further stopped based on the occurrence information output by the output means. That is, when a welding defect occurs, the welding robot is stopped by the stopping means. In this way, by stopping the welding robot in response to the occurrence of a welding defect, it is possible to prevent the occurrence of a defect from being overlooked. Furthermore, by being able to take appropriate action at the time when a welding defect occurs, it is possible to prevent the occurrence of welding defects from continuing.

[0031] In addition, the predetermined threshold may be selected by a user from among a first threshold, a second threshold, and a third threshold.

[0032] According to the present invention, the user is allowed to select a predetermined threshold from among the first threshold, the second threshold, and the third threshold. This allows the welding conditions required by the user to be flexibly accommodated, thereby improving user convenience.

[0033] The defect information output device may further include a memory control means for causing a memory unit to store a log relating to a position of the welding robot when the output means outputs the defect information.

[0034] According to the present invention, the apparatus further includes a memory control means for causing a log relating to the position when the output means outputs the defect information to be stored in the memory unit. That is, the defect information is stored in association with the position of the welded portion related to the defect information. Therefore, after the welding operation, it is possible to easily check which part of the welded portion has a defect or a possible defect.

[0035] The output means may further include a memory control means for storing in a memory unit information indicating which of the length or the width measured by the measuring means is based on which the output means outputs the defect information.

[0036] According to this invention, the output means further includes a memory control means for storing in the memory unit information indicating which of the length or width measured by the measuring means was used when the output means output the defect information. In other words, the memory unit stores information indicating whether there was a problem with the length or width of the molten pool with respect to the defect information. In this way, by accurately grasping the details of the information related to the welding defect, it is possible to easily determine how to deal with the defect.

[0037] The measuring means may measure the length or the width based on a luminance of the image data.

[0038] According to this invention, the measuring means measures the length or width of the molten pool based on the brightness of the image data. In other words, the portion of the molten metal forming the molten pool that is in a state of luminescence due to high temperature is recognized as the molten pool. The length or width of the portion recognized as the molten pool is then measured by the measuring means. This makes it possible to exclude the portion of the molten pool after it has hardened from the length or width to be measured. Therefore, only the molten pool before hardening, which is likely to cause welding defects, can be targeted for measurement.

[0039] The welding robot may further include a welding torch provided on the welding robot, and the position of the welding torch may be changed without changing the position of the imaging means.

[0040] According to this invention, the position of the welding torch is changed without changing the position of the imaging means. In other words, the imaging means does not follow the change in the position of the welding torch. The change in the length or width of the molten pool is measured as a continuous change. Therefore, even if the relative position between the imaging means and the molten pool changes due to the change in the position of the welding torch, the detection of dripping can be continued without being affected by the change in the relative position. Therefore, by not having the imaging means follow the change in the position of the welding torch, it is possible to prevent, for example, blurring of the image data captured by the imaging means due to the imaging means following the change in the position of the welding torch. In other words, it is possible to prevent the measurement by the measurement means from being affected by a change in the orientation of the imaging means.

[0041] The steel material may be a steel pipe having a curved portion.

[0042] According to the present invention, the steel material is a steel pipe having a curved portion. By applying the welding system according to the present invention to a steel pipe having a curved portion, the above-mentioned advantageous effects can be significantly achieved.

[0043] The defect may also be characterized as drooling of the molten pool or humping of the weld bead.

[0044] According to the present invention, the welding defect is dripping of the molten pool or humping of the weld bead. Dripping of the molten pool or humping of the weld bead can be prevented by detecting symptoms during the welding operation and taking appropriate measures. The above-mentioned configuration can prevent the above defects, thereby contributing to more efficient welding operations. Effect of the Invention

[0045] According to the present invention, it is possible to provide a welding system capable of detecting welding defects during welding work. [Brief description of the drawings]

[0046] [Figure 1] 1 is a perspective view of a welding system according to the present invention; [Diagram 2] FIG. 2 is an enlarged view of a welding robot according to the present invention. [Diagram 3] FIG. 2 is a block diagram showing a configuration of a processing unit. [Figure 4] 1 is an example showing the length and width of the molten pool. [Diagram 5] FIG. 2 is an enlarged plan view of a curved portion of a steel pipe. [Figure 6] FIG. 13 is a diagram showing the state in which a curved portion of a steel pipe is being welded by a welding robot. [Figure 7] FIG. 2 is a schematic plan view of a case where a curved portion of a steel pipe is welded by a welding robot. [Figure 8] 1 is a first example of a molten pool imaged by an imaging means. [Figure 9] 13 is a second example of the molten pool imaged by the imaging means. [Figure 10] 1 is an example of a graph showing the length of a molten pool measured by a measuring means. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0047] Hereinafter, a welding system 100 according to an embodiment of the present invention will be described with reference to the drawings. The welding system 100 is used when welding steel materials. In this embodiment, the steel materials are steel pipes P having curved portions R. The steel pipes P are used, for example, as pillars of buildings. The welding system 100 controls a welding robot 20. As shown in FIG. 1 or FIG. 2, the welding system 100 includes a guide rail 10, a welding robot 20, an imaging means 30, and a processing unit 40.

[0048] The guide rail 10 is attached in a ring shape around the steel pipe P. A welding robot 20 is disposed on the guide rail 10. In this embodiment, one direction in the circumferential direction of the guide rail 10 is referred to as a predetermined direction Y1, and the direction opposite to the predetermined direction Y1 is referred to as an opposite direction Y2. The welding robot 20 welds the steel pipe P while moving in a predetermined direction Y1 over the steel pipe P. In this embodiment, the welding robot 20 welds the steel pipe P by vertical upward welding and horizontal welding. As shown in FIG. 2 , the welding robot 20 at least includes a main body 21, a welding torch 22, an arm 23, a welding cable 24, and a fixing member 25.

[0049] The main body 21 is a portion that serves as a base of the welding robot 20. The main body 21 includes a case portion 21a and a slide portion 21b. The case portion 21a accommodates therein the main components of the welding robot 20. Furthermore, an imaging means 30, which will be described later, is provided on the outer surface of the case portion 21a.

[0050] The slide portion 21b is a portion disposed on the guide rail 10. The welding robot 20 moves in a predetermined direction Y1 or an opposite direction Y2 by the slide portion 21b sliding against the guide rail 10. The case portion 21a and the slide portion 21b are capable of relative movement. Specifically, the case portion 21a can move in a first axial direction X1, which is one direction along the axial direction of the steel pipe P, and in a second axial direction X2, which is the other direction, with the slide portion 21b as a reference, in a first direction Z1, which is a direction away from the steel pipe P, and in a second direction Z2, which is a direction approaching the steel pipe P. Any configuration is suitably used for the relative movement between the main body portion 21 and the slide portion 21b. For example, the case portion 21a is moved by an actuator disposed between the main body portion 21 and the slide portion 21b.

[0051] The welding torch 22 is a part that welds the steel pipes P together. Arc welding is suitably used for welding by the welding torch 22. The steel pipes P are welded together by discharging electricity from the tip of the welding torch 22 toward the welded portion of the steel pipes P. Arm portion 23 is provided between main body portion 21 and welding torch 22, and supports welding torch 22. Arm portion 23 is capable of changing the inclination angle of welding torch 22. Specifically, as shown in FIG. 2, arm portion 23 can change the inclination angle of welding torch 22 by moving the tip of welding torch 22 in a first circumferential direction T1, which is a direction along a predetermined direction Y1, and in a second circumferential direction T2, which is a direction along the opposite direction Y2.

[0052] In addition, the arm portion 23 is capable of changing the inclination angle of the welding torch 22 by moving the tip of the welding torch 22 in a first orthogonal direction B1, which is a direction perpendicular to the specified direction Y1 and the opposite direction Y2, and in a second orthogonal direction B2, which is a direction opposite to the first orthogonal direction B1. When welding the steel pipes P, an erection jig E is provided to temporarily fix the steel pipes P together, as shown in Fig. 1. Therefore, by changing the inclination angle of the welding torch 22 by the arm portion 23 as described above, interference between the erection jig E and the welding torch 22 is prevented.

[0053] One end of welding cable 24 is connected to welding torch 22 of welding robot 20, and the other end is connected to a device (e.g., a wire feeder not shown) different from welding robot 20. The welding cable serves to supply welding wire toward welding torch 22 and to apply voltage to welding torch 22.

[0054] The fixing member 25 fixes a portion between one end of the welding cable 24 and the other end of the welding cable 24 to the main body 21 of the welding robot 20. Hereinafter, this portion may be referred to as a fixed portion. By gripping the fixed portion with the fixing member 25, even if the other end of the welding cable 24 is pulled further than the fixed portion as the welding robot 20 moves along the guide rail 10, the welding cable 24 between one end of the welding cable 24 and the fixed portion will not move relative to the main body 21. In this manner, fixing member 25 serves to prevent welding torch 22 connected to one end of the welding cable from being pulled by the welding cable and becoming displaced.

[0055] The imaging means 30 captures an image of a molten pool M of steel materials being welded by the welding robot 20. Here, the molten pool M refers to a weld bead WB that is generated when steel materials are welded, before it hardens, as shown in Fig. 3. The imaging means 30 includes an opposite side camera 31, a predetermined direction side camera 32, a camera arm 33, and a camera slide unit 34.

[0056] The opposite side camera 31 is provided on a side surface of the main body 21 of the welding robot 20, the side surface opposite to the side in the predetermined direction Y1. The opposite side camera 31 images the molten pool M from a position relative to the welding torch 22 and opposite to the predetermined direction Y1. In other words, the opposite side camera 31 images the state immediately after the molten pool M is generated between the steel pipes P welded by the welding torch 22.

[0057] The predetermined direction camera 32 is provided on a side surface of the main body 21 of the welding robot 20, the side surface facing the predetermined direction Y1. The predetermined direction camera 32 captures an image of the molten pool M from a position relative to the welding torch 22 and on the side of the predetermined direction Y1. The camera arm 33 is a rod-shaped member that attaches the opposite side camera 31 and the predetermined direction side camera 32 to the side surface of the main body 21. The opposite side camera 31 or the predetermined direction side camera 32 is attached to one end of the camera arm 33. At this time, it is preferable that a ball joint, for example, is provided between the camera arm 33 and the opposite side camera 31 or the predetermined direction side camera 32, and that the angle can be adjusted by the ball joint. The angle adjustment may be performed, for example, manually or by controlling an actuator.

[0058] The angle adjustment of the opposite side camera 31 and the predetermined direction side camera 32 by the ball joint is preferably performed as follows. Here, when the tip of the welding torch 22 moves in the first circumferential direction T1 or the second circumferential direction T2, the relative position of the tip of the welding torch 22 changes with respect to the opposite side camera 31 and the predetermined direction side camera 32. In such a case, it is preferable to perform adjustment so that the entire range in which the tip of the welding torch 22 can move is included in the field of view of both the opposite side camera 31 and the predetermined direction side camera 32. The other end of the camera arm 33 is attached to a camera slide portion 34 .

[0059] The camera slide 34 is a rail-like member to which the other end of the camera arm 33 is attached. The camera slide 34 is attached to a side surface of the main body 21 of the welding robot 20. The camera slide 34 supports the camera arm 33 so that it can slide in the first axial direction X1 and the second axial direction X2. This allows the opposite side camera 31 and the predetermined direction side camera 32 to move relative to the main body 21 in the first axial direction X1 and the second axial direction X2. The relative movement is performed, for example, by controlling an actuator.

[0060] The relative movement of the opposite side camera 31 and the predetermined direction side camera 32 with respect to the main body 21 is performed, for example, to prevent the opposite side camera 31 and the predetermined direction side camera 32 from moving following the movement of the main body 21 in the first axial direction X1 or the second axial direction X2. This prevents the opposite side camera 31 and the predetermined direction side camera 32 from moving relative to the molten pool M generated in the welded portion of the steel pipe P.

[0061] Therefore, during welding operation, when the main body 21 moves in the predetermined direction Y1 or the opposite direction Y2, and the first direction Z1 or the second direction Z2, the opposite side camera 31 and the predetermined direction camera 32 move following the movement. In contrast, even if the main body 21 moves in the first axial direction X1 or the second axial direction X2, the opposite side camera 31 and the predetermined direction camera 32 do not follow the movement.

[0062] As described above, welding torch 22 and arm unit 23 supporting welding torch 22 are also provided on main body 21 of welding robot 20. The position of welding torch 22 is changed by arm unit 23. Therefore, the position of welding torch 22 is changed without changing the position of imaging means 30. In other words, imaging means 30 does not follow the movement of welding torch 22.

[0063] Here, when a sign of a welding defect occurring during welding work is detected, the inclination angle of welding torch 22 may be changed in order to avoid the occurrence of the defect (described later). At this time, the relative positions of the tip of welding torch 22, opposite side camera 31, and predetermined direction side camera 32 change. In other words, the so-called aiming angle when imaging welding torch 22 by imaging means 30 changes.

[0064] The movement of main body 21 in first direction Z1 and second direction Z2, or first axial direction X1 and second axial direction X2, according to the above-mentioned configuration is performed in order to image the tip of welding torch 22 from a more suitable position by opposite side camera 31 and specified direction camera 32 when the relative position between the tip of welding torch 22 and opposite side camera 31 and specified direction camera 32 changes as described above.

[0065] The processing unit 40 is a calculation device for appropriately controlling each of the above-mentioned components in accordance with the welding work of the steel pipe P. The processing unit 40 is disposed inside the case 21a of the welding robot 20. As shown in Fig. 4, the processing unit 40 includes a measurement means 41, an output means 42, an acquisition means 43, a memory control means 44, a memory unit 45, a detection means 46, a control means 47, a change means 48, and a stop means 49.

[0066] The measuring means 41 measures the length L or width W of the molten pool M based on image data output by the imaging means 30 after imaging the molten pool M. Specifically, the measuring means 41 measures the length L or width W based on the brightness of the image data. Here, the length L is the dimension of the molten pool M in the circumferential direction of the steel pipe P, as shown in Fig. 3. The width W is the dimension in the direction perpendicular to the length L.

[0067] The measuring means 41 measures the length L or width W of the molten pool M based on, for example, image data output by the opposite side camera 31 after capturing an image of the molten pool M. Alternatively, the measuring means 41 measures the width W of the molten pool M based on image data output by the predetermined direction side camera 32 after capturing an image of the molten pool M. The length L and width W can be measured by detecting the length L of the molten pool M shown in Fig. 3 and detecting the width W in a direction perpendicular to the longitudinal direction.

[0068] It is preferable that the length L and width W of the molten pool M satisfy, for example, the following conditions. In the following description, the radius of curvature r of the curved portion R of the steel pipe P shown in Fig. 5 is 40 mm. It is also preferable that the length L of the molten pool M be maintained at 20 mm ± 10 mm. 6 and 7, when the welding robot 20 passes through the curved section R of the steel pipe P, the shape of the molten pool M imaged by the imaging means 30 changes. Specifically, as shown in Figures 8 and 9, when the welding robot 20 enters the curved section R or when the welding robot 20 exits the curved section R, the length L of the molten pool M changes continuously.

[0069] In contrast, when the radius of curvature r of the curved portion R of the steel pipe P is 40 mm, and the length L of the molten pool M is 20 mm, the length L of the molten pool M will appear almost the same as in the straight section even during welding of the curved portion R. For this reason, controlling the movement of the main body 21 described above so that the relative positions of the opposite side camera 31 and the specified direction side camera 32, and the tip of the welding torch 22 do not change, contributes to imaging the tip of the welding torch 22 by the imaging means 30 under the same conditions.

[0070] As described above, the opposite side camera 31 captures an image of the state immediately after the formation of the molten pool M, and is therefore suitable for measuring the length L of the molten pool M. In contrast, since the molten pool M is not located on the side where the predetermined direction side camera 32 is located, the length L of the molten pool M cannot be measured from the image captured by the predetermined direction side camera 32. For this reason, only the width W of the molten pool M is measured from the image captured by the predetermined direction side camera 32.

[0071] The output means 42 outputs defect information regarding defects in welding performed by the welding robot 20, based on the length L or width W measured by the measurement means 41. In this embodiment, the welding defect is dripping of the molten pool M or humping of the weld bead WB.

[0072] Dripping of the molten pool M occurs when the amount of welding wire that constitutes the molten pool M between the steel pipes P becomes excessive, causing the molten pool M to become heavy. Dripping of the molten pool M occurs, for example, when the supply speed of the welding wire becomes excessive compared to the movement speed of the welding robot 20. When dripping of the molten pool M occurs, it is characterized in that the width W of the molten pool M is large compared to the length L of the molten pool M. Depending on the molten pool M in the area where dripping occurs, a sufficient weld bead WB will not be formed, resulting in poor welding.

[0073] Humping occurs when the molten pool M is interrupted between the steel pipes P. Humping occurs when the amount of welding wire that constitutes the molten pool M between the steel pipes P is insufficient. Humping occurs, for example, when the movement speed of the welding robot 20 is excessive relative to the supply speed of the welding wire. When humping occurs, it is characterized in that the width W of the molten pool M is small compared to the length L of the molten pool M. It is also characterized in that the molten pool M is longer than when normal welding is performed. A sufficient weld bead WB is not formed due to the molten pool M in the area where humping occurs, resulting in poor welding.

[0074] The defect information output by the output means 42 includes symptom information and occurrence information. The symptom information is information on a symptom of a defect, that is, information on a symptom of the occurrence of dripping of the molten pool M or humping of the weld bead WB. An indication of drooping of the molten pool M is, for example, that the width W of the molten pool M becomes larger than a standard, or that the ratio of the width W of the molten pool M to the length L of the molten pool M becomes larger than a standard. A symptom of humping is, for example, that the length L of the molten pool M becomes larger than the standard, or that the ratio of the width W of the molten pool M to the length L of the molten pool M becomes smaller than the standard. The symptom information is output by the output means 42 based on the value of the length L or width W measured by the measuring means 41.

[0075] The occurrence information is information about the occurrence of a defect, that is, information about the occurrence of dripping of the molten pool M or humping of the weld bead WB. The occurrence information is output by the output means 42 based on the fact that the change (differential value) of the length L or width W measured by the measurement means 41 exceeds a predetermined threshold value.

[0076] The predetermined threshold is determined for the length L or width W of the molten pool M. When dripping or humping of the molten pool M occurs, the molten pool M is interrupted, causing the length L or width W of the molten pool M to suddenly decrease. This type of change is characterized by a sudden change, for example, as shown in defect occurrence portion X in the graph of the length L of the molten pool M versus time in FIG. 10. In defect occurrence portion X shown in FIG. 10, the amount of change in the length L of the molten pool M is -5 mm. For this reason, in this embodiment, the threshold for the amount of change in the length L of the molten pool M related to the generation information can be set to -5 mm. Alternatively, if there is a symptom of dripping or humping of the molten pool M, the length L of the molten pool M will increase beyond a threshold. In the graph of Fig. 10, the defect occurrence portion X occurs immediately after the length L of the molten pool M exceeds 26 mm. For this reason, in this embodiment, the threshold value of the length L of the molten pool M related to the symptom information can be set to 26 mm.

[0077] The predetermined threshold for determining that dripping or humping of the molten pool M has occurred can be set appropriately according to the welding conditions of each user. Specifically, for example, the predetermined threshold can be selected by the user from a first threshold, a second threshold, and a third threshold that are determined in advance. The selection is preferably performed by, for example, a control panel or the like provided in the welding system 100.

[0078] In this embodiment, the output means 42 outputs symptom information of dripping of the weld bead WB in the following cases, for example. (1) The output means 42 determines whether the width W of the molten pool M measured by the measuring means 41 is larger than a predetermined width threshold used to detect dripping of the weld bead WB, and the output means 42 determines that it is longer. (2) The output means 42 determines whether the ratio of the width W of the molten pool M to the length L of the molten pool M measured by the measurement means 41 is greater than a predetermined standard threshold value used to detect dripping of the weld bead WB, and the output means 42 determines that it is greater.

[0079] In the present embodiment, the output means 42 outputs information on the occurrence of dripping of the weld bead WB in the following cases, for example. (1) The output means 42 determines whether the change in length L or width W of the molten pool M measured by the measuring means 41 is greater than a predetermined length change threshold or a predetermined width change threshold used to detect dripping of the weld bead WB, and the output means 42 determines that it is greater.

[0080] Furthermore, in this embodiment, the output means 42 outputs symptom information of humping of the weld bead WB in the following cases, for example. (1) The output means 42 determines whether the length L of the molten pool M measured by the measurement means 41 is longer than a predetermined length threshold used to detect humping of the weld bead WB, and the output means 42 determines that it is longer. (2) The output means 42 determines whether the width W of the molten pool M measured by the measurement means 41 is smaller than a predetermined width threshold used to detect humping of the weld bead WB, and the output means 42 determines that it is smaller. (3) The output means 42 determines whether the ratio of the width W of the molten pool M to the length L of the molten pool M measured by the measurement means 41 is smaller than a predetermined standard threshold value used to detect humping of the weld bead WB, and the output means 42 determines that the ratio is smaller.

[0081] In this embodiment, the output means 42 outputs information on the occurrence of humping of the weld bead WB in the following cases, for example. (1) When the output means 42 determines whether the width W of the molten pool M measured by the measuring means 41 is smaller than a predetermined width threshold used to detect humping of the weld bead WB, and the output means 42 determines that it is smaller, and when the output means 42 determines whether the change in the length L of the molten pool M measured by the measuring means 41 is greater than a predetermined length change threshold used to detect humping of the weld bead WB, and the output means 42 determines that it is greater. (2) The output means 42 determines whether the change in length L or width W of the molten pool M measured by the measuring means 41 is greater than a predetermined length / width change threshold used to detect humping of the weld bead WB, and the output means 42 determines that it is greater.

[0082] The acquiring means 43 acquires the construction jig position information indicating the position of the construction jig E. As described above, the construction jig E is a jig for temporary fastening that is provided to connect the ends of the steel pipe P as shown in FIG. 1. When welding the steel pipe P by the welding system 100, the welding is performed with this jig attached. Therefore, depending on the position of the imaging means 30, the construction jig E may interfere with the field of view of the opposite side camera 31 or the predetermined direction side camera 32, making it impossible to image the molten pool M. Therefore, by the acquiring means 43 acquiring the position information of the construction jig E, the information is used as a reference for taking measures such as visually checking the part of the molten pool M where the construction jig E prevented the image from being captured by the construction jig E by the worker. The acquisition means 43 acquires position information of the construction jig E based on, for example, the sensing processing result of the sensing processing unit. The sensing processing unit is a part that performs sensing processing for acquiring the position of the construction jig E. The acquisition means 43 may acquire position information of the construction jig E based on the input result of the input unit. The input unit is a part that allows the user to input the position of the construction jig E.

[0083] The storage control means 44 is a part for storing information in the storage unit 45. The storage control means 44 is, for example, a known writing device used in computers, etc. Specifically, for example, it is a part of the processing block of a CPU. The memory control means 44 stores in the memory unit 45 a log relating to, for example, the position of the welding robot 20 when the output means 42 outputs the defect information and whether the defect information output from the output means 42 at that position is occurrence information or symptom information. This information is used to identify in which part a defect has occurred after the welding work.

[0084] The memory control means 44 causes the memory unit 45 to store information indicating which of the length L or width W measured by the measuring means 41 was used when the output means 42 output the defect information in association with whether the defect information is occurrence information or symptom information. This information is used, for example, to investigate on what basis the welding system 100 determined that a defect has occurred.

[0085] Alternatively, based on the construction jig position information acquired by the acquisition means 43, the position of the welding robot 20 where the molten pool M cannot be imaged by the opposite side camera 31 is stored as a log in the storage unit 45. This information is used to identify which parts need to be visually checked after the welding work.

[0086] The storage unit 45 is a portion where the above-mentioned information is stored by the storage control means 44. The storage unit 45 is, for example, a storage device such as a portable medium such as a flexible disk, a magneto-optical disk, a ROM, or a CD-ROM, or a hard disk built into a computer system.

[0087] The detection means 46 detects burn-through in welding by the welding robot 20 based on image data output by capturing an image of the molten pool M by the predetermined direction camera 32. Burn-through refers to a phenomenon in which the molten pool M generated during welding operation forms a liquid surface on the surface (e.g., the inner peripheral surface of the steel pipe P) opposite the surface (e.g., the outer peripheral surface of the steel pipe P) on the side where the welding torch 22 approaches the steel pipe P, and the molten pool M is blown to the opposite side by the pressure of the arc, penetrating the steel material. This burn-through is also a factor in preventing the formation of a sufficient weld bead WB in the welded portion between the steel pipes P, and is therefore one of the welding defects.

[0088] The control means 47 controls the imaging means 30. For example, when the welding robot 20 moves in the predetermined direction Y1, the imaging means 30 controls the opposite side camera 31 to image the molten pool M from a position relative to the welding torch 22 on the opposite side of the predetermined direction Y1. Also, when the welding robot 20 turns around and moves in the opposite direction to the predetermined direction Y1 (opposite direction Y2), the imaging means 30 controls the predetermined direction camera 32 to image the molten pool M from a position relative to the welding torch 22 on the side of the predetermined direction Y1. In this way, the control means 47 contributes to enabling the imaging of the molten pool M to be performed at any time.

[0089] The change means 48 changes the state of the welding robot 20 based on the symptom information output by the output means 42. This prevents dripping or humping of the molten pool M during welding work. The state of the welding robot 20 refers to the speed at which the welding robot 20 moves in the predetermined direction Y1, the inclination angle of the welding torch 22 of the welding robot 20 relative to the predetermined direction Y1, the speed at which the welding robot 20 feeds the welding wire, or the distance between the groove formed in the steel material and the tip of the welding torch 22 of the welding robot 20.

[0090] Specifically, for example, when a sign of dripping of the molten pool M is detected, the state is changed as follows: That is, the moving speed of the welding robot 20 is increased. The tilt angle of the welding torch 22 is changed by the arm unit 23 of the welding robot 20 as follows: That is, for example, while maintaining or increasing the moving speed of the welding robot 20, the welding torch 22 is tilted so that the tip of the welding torch 22 moves toward the traveling direction. The speed at which the welding wire is fed to the welding torch 22 is reduced. The distance between the groove formed in the steel material and the tip of the welding torch 22 held by the welding robot 20 is increased.

[0091] Furthermore, if a symptom of humping is detected, the state is changed as follows. That is, the moving speed of welding robot 20 is reduced. The tilt angle of welding torch 22 is changed by arm unit 23 of welding robot 20 as follows. That is, for example, while maintaining or reducing the moving speed of welding robot 20, welding torch 22 is tilted so that the tip of welding torch 22 moves to the side opposite the traveling direction. The speed at which welding wire is fed to welding torch 22 is increased. The distance between the groove formed in the steel material and the tip of welding torch 22 held by welding robot 20 is reduced.

[0092] The stopping means 49 stops the welding robot 20 based on the generated information output by the output means 42. In this way, when a welding defect occurs during the welding operation, the stopping means 49 prevents the welding robot 20 from continuing the welding operation. For example, the stopping means 49 stops the movement of the welding robot 20. At this time, the welding torch 22 may be moved away from the outer peripheral surface of the steel pipe P. Alternatively, the stopping means 49 may stop the welding robot 20 by turning off the power to the welding robot 20 and stopping its function.

[0093] Each component of the processing unit 40, except for the storage unit 45, includes a processor such as a CPU (Central Processing Unit) and a memory connected by a bus, and executes a preconfigured control program to ensure the respective functions. Also, each component may be realized using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array). Also, the program for controlling the processing unit 40 may be recorded on a computer-readable recording medium.

[0094] The computer-readable recording medium is, for example, a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, etc., or a storage device such as a hard disk built into a computer system. The program may be transmitted via a telecommunication line. Alternatively, the area of ​​the storage unit 45 may be appropriately divided to ensure an area for storing the program that controls the processing unit 40. Alternatively, the program may be stored in a storage device different from the storage unit 45.

[0095] As described above, in the welding system 100 according to the present embodiment, the imaging means 30 images the molten pool M and outputs image data. The measuring means 41 measures the length L or width W of the molten pool M based on the output image data. The output means 42 outputs defect information related to defects in welding by the welding robot 20 based on the measured length L or width W of the molten pool M. Here, if the molten pool M before hardening drips during welding, the length L or width W of the molten pool M will rapidly decrease. Alternatively, if the molten pool M of the weld is not continuous but is interrupted midway, a portion where the molten pool M is not formed will be generated. For these events, by providing the above-mentioned configuration, it is possible to quickly detect the dripping or interruption of the molten pool M before hardening during welding. This contributes to higher welding quality.

[0096] The imaging means 30 also includes an opposite side camera 31 provided on a side of the welding robot 20 opposite to the side in the predetermined direction Y1 in which the welding robot 20 advances. That is, the opposite side camera 31 is attached to the side of the welding robot 20 and images the molten pool M from the opposite side of the traveling direction. This makes it possible to image the area where the welding robot 20 has welded and where the molten pool M has been generated, by tracking the area as the welding robot 20 moves. This makes it easier to grasp the width W and length L of the molten pool M more accurately.

[0097] Furthermore, the imaging means 30 images the molten pool M from a position relative to the welding torch 22, on the opposite side to the predetermined direction Y1 in which the welding robot 20 advances. This makes it possible to image the molten pool M immediately after the molten pool M is generated. This makes it possible to more accurately image the molten pool M in a state before hardening begins.

[0098] Furthermore, the memory control means 44 stores, as a log in the memory unit 45, the position of the welding robot 20 where the molten pool M cannot be imaged by the opposite side camera 31, based on the position information of the construction jig E acquired by the acquisition means 43. Here, when the welding robot 20 welds the vicinity of the construction jig E attached to the steel material, the construction jig E may interfere with the field of view of the imaging means 30, making it impossible to image the state of the molten pool M. In response to this, by storing the position where the molten pool M cannot be imaged as a log in the memory unit 45, the position can be easily confirmed after the welding work. Therefore, the confirmation work after welding can be efficiently performed.

[0099] The measuring means 41 measures the length L or width W based on image data output by the opposite side camera 31 after capturing an image of the molten pool M, and measures the width W based on image data output by the predetermined direction side camera 32 after capturing an image of the molten pool M. As a result, even if the opposite side camera 31 cannot capture an image of the molten pool M due to, for example, interference of the construction jig E with the field of view of the opposite side camera 31, the predetermined direction side camera 32 can capture at least the width W of the molten pool M. In this way, by providing the predetermined direction side camera 32, which has an auxiliary role, in the imaging means 30, imaging can be performed more stably. Furthermore, by providing cameras on both the predetermined direction Y1 side and the opposite direction Y2 side, when the traveling direction of the welding robot 20 changes, at least the width W of the molten pool M can be measured by either camera. Alternatively, the predetermined direction side camera 32 and the opposite side camera 31 can switch roles. As a result, imaging can be performed more stably.

[0100] Furthermore, the measuring means 41 measures the length L or width W of the molten pool M based on image data output by the opposite side camera 31 after capturing an image of the molten pool M. In addition, the detecting means 46 detects burn-through in welding by the welding robot 20 based on image data output by the predetermined direction side camera 32 after capturing an image of the molten pool M. In this way, by simultaneously measuring the length L or width W of the molten pool M by the measuring means 41 and detecting burn-through by the detecting means 46, it is possible to more reliably detect welding defects.

[0101] Furthermore, when the welding robot 20 moves in the predetermined direction Y1, the control means 47 controls the opposite side camera 31 to capture an image of the molten pool M from a position relative to the welding torch 22 that is opposite to the predetermined direction Y1, and when the welding robot 20 turns around and moves in the opposite direction to the predetermined direction Y1, the control means 47 controls the predetermined direction camera 32 to capture an image of the molten pool M from a position relative to the welding torch 22 on the side of the predetermined direction Y1. This allows the imaging means 30 to continue capturing an image of the molten pool M regardless of which side the welding robot 20 moves to.

[0102] The defect information also includes symptom information on symptoms of a defect, and the symptom information is output by output means 42 based on the value of length L or width W measured by measurement means 41. In this way, by outputting symptom information on symptoms of a defect by output means 42 in addition to welding defect information, it is possible to detect the occurrence of a welding defect before it occurs and to respond quickly, thereby further improving the quality of the welding.

[0103] The system further includes a change means 48 that changes the state of the welding robot 20 based on the symptom information output by the output means 42. In this manner, by appropriately changing the state of the welding robot 20 in response to the symptom of a welding defect, it is possible to prevent the occurrence of a welding defect.

[0104] In addition, the state of the welding robot 20 changed by the change means 48 includes the speed at which the welding robot 20 moves in a predetermined direction Y1, the inclination angle of the welding torch 22 held by the welding robot 20 relative to the predetermined direction Y1, the speed at which the welding robot 20 feeds the wire, and the distance between the groove formed in the steel material and the tip of the welding torch 22 held by the welding robot 20.

[0105] By changing the movement speed of the welding robot 20, the time that the welding torch 22 stays at any position in the welded portion can be adjusted. By changing the tilt angle of the welding torch 22, the effect on the shape of the molten pool M after welding can be adjusted. By changing the speed at which the wire is fed, the amount of material that becomes the molten pool M after welding can be adjusted. By changing the distance between the groove and the tip of the welding torch 22, the temperature of the welded portion can be adjusted. In this way, by appropriately changing the welding robot 20 using the changing means 48, the possibility of occurrence of welding defects can be minimized.

[0106] The defect information also includes occurrence information regarding the occurrence of a defect, and the occurrence information is output by the output means 42 based on the fact that the change in the length L or width W of the molten pool M measured by the measurement means 41 exceeds a predetermined threshold. In this manner, the occurrence of a welding defect can be detected by outputting the information that a defect has occurred by the output means 42.

[0107] The system further includes a stopping means 49 that stops the welding robot 20 based on the occurrence information output by the output means 42. In other words, when a welding defect occurs, the stopping means 49 stops the welding robot 20. In this way, by stopping the welding robot 20 in response to the occurrence of a welding defect, it is possible to prevent the occurrence of a defect from being overlooked. Also, by being able to take appropriate action at the time when a welding defect occurs, it is possible to prevent the occurrence of welding defects from continuing.

[0108] In addition, the user is allowed to select a predetermined threshold from among the first threshold, the second threshold, and the third threshold. This allows the welding conditions required by the user to be flexibly accommodated, thereby improving user convenience.

[0109] The apparatus further includes a storage control means 44 for storing in a storage unit 45 a log relating to the position when the output means 42 outputs the defect information. In other words, the defect information is stored in association with the position of the welded portion related to the defect information. Therefore, after the welding operation, it is possible to easily check which part of the welded portion has a defect or a possible defect.

[0110] The output means 42 further includes a memory control means 44 for storing, in the memory unit 45, information indicating which of the length L or width W measured by the measuring means 41 was used as a basis when the output means 42 output the defect information. In other words, with regard to the defect information, whether there was a problem with the length L or the width W of the molten pool M is stored in the memory unit 45. In this way, by accurately grasping the details of the information related to the welding defect, it is possible to easily decide how to deal with the defect.

[0111] Furthermore, the measurement means 41 measures the length L or width W of the molten pool M based on the brightness of the image data. In other words, the portion of the molten metal forming the molten pool M that is in a state of luminescence due to high temperature is recognized as the molten pool M. The measurement means 41 then measures the length L or width W of the portion recognized as the molten pool M. This makes it possible to exclude the portion of the molten pool M after it has hardened from the measured length L or width W. Therefore, only the molten pool M before hardening, where welding defects may occur, can be targeted for measurement.

[0112] In addition, the position of the welding torch 22 is changed without changing the position of the imaging means 30. In other words, the imaging means 30 does not follow the change in the position of the welding torch 22. The change in the length or width W of the molten pool M is measured as a continuous change. Therefore, even if the relative position between the imaging means 30 and the molten pool M changes due to the change in the position of the welding torch 22, the detection of dripping can be continued without being affected by the change in the relative position. Therefore, by not following the change in the position of the welding torch 22, it is possible to prevent the image data captured by the imaging means 30 from being blurred by, for example, the imaging means 30 following the change in the position of the welding torch 22. In other words, it is possible to prevent the measurement by the measurement means 41 from being affected by the change in the orientation of the imaging means 30.

[0113] Moreover, the steel material is a steel pipe P having a curved portion R. By applying the welding system 100 according to the present invention to the steel pipe P having a curved portion R, the above-mentioned operational effects can be significantly achieved.

[0114] The welding defect is dripping of the molten pool M or humping of the weld bead. Dripping of the molten pool M or humping of the weld bead can be prevented by detecting symptoms during welding and taking appropriate measures. The above-mentioned configuration can prevent the above-mentioned defects, thereby contributing to more efficient welding work.

[0115] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the camera arm 33 may have an extendable structure. Furthermore, the processing section does not have to be disposed inside the main body of the welding robot 20. For example, the processing section may be provided in an external device and connected to the main body via a cable.

[0116] In addition, within the scope of the invention, the components in the above-described embodiments may be replaced with well-known components, and the above-described modified examples may be combined as appropriate. [Explanation of symbols]

[0117] 20 Welding robot 22 Welding torch 30 Imaging means 31 Opposite Camera 32 Camera in a specific direction 41 Measurement methods 42 Output Method 43 Acquisition means 44 Storage control means 45 Storage section 46 Detection Methods 47 Control Means 48 Means of modification 49 Stopping means 100 Welding System E Construction jig M Molten pool P steel pipe R curved part W width WB Weld bead Y1 Specified direction

Claims

1. A welding system for controlling a welding robot that moves on a steel material in a predetermined direction while welding the steel material, an imaging means for imaging a molten pool of the steel material being welded by the welding robot; a measuring means for measuring a length or a width of the molten pool based on image data output by the imaging means after imaging the molten pool; an output means for outputting defect information regarding defects in welding performed by the welding robot based on the ratio of the width to the length measured by the measuring means; Equipped with the defect information includes symptom information regarding a symptom of the defect; The welding system is characterized in that the symptom information is output by the output means when it is determined that the ratio of the width to the length measured by the measuring means is greater than a predetermined reference threshold value used to detect dripping of a weld bead.

2. Except when the imaging means is an infrared camera, The welding system of claim 1 .

3. An erection jig provided on the steel material; An acquisition means for acquiring construction jig position information indicating the position of the construction jig; A storage control means; Further comprising: the imaging means includes an opposite side camera provided on a side surface of the welding robot opposite to the side of the predetermined direction, The memory control means stores in a memory unit as a log the position of the welding robot where the molten pool cannot be imaged by the opposite camera based on the position information of the construction jig acquired by the acquisition means.

3. The welding system according to claim 1 or 2.

4. The imaging means is an opposite side camera provided on a side of the welding robot opposite to the predetermined direction; a predetermined direction camera provided on a side surface of the welding robot on the side facing the predetermined direction; Including, the measuring means measures the length or the width based on image data outputted by the opposite side camera after capturing an image of the molten pool, and measures the width based on image data outputted by the predetermined direction side camera after capturing an image of the molten pool. The welding system according to any one of claims 1 to 3.

5. Detection means, Further comprising: The imaging means is an opposite side camera provided on a side of the welding robot opposite to the predetermined direction; a predetermined direction camera provided on a side surface of the welding robot on the side facing the predetermined direction; Including, The measuring means measures the length or the width based on image data output by the opposite camera after capturing an image of the molten pool, The detection means detects burn-through of welding by the welding robot based on image data output by the predetermined direction side camera after capturing an image of the molten pool. The welding system according to any one of claims 1 to 4.

6. A welding torch provided on the welding robot; A control means; Further comprising: The imaging means is an opposite side camera provided on a side of the welding robot opposite to the predetermined direction; a predetermined direction camera provided on a side surface of the welding robot on the side facing the predetermined direction; Including, The control means When the welding robot moves in the predetermined direction, the opposite side camera is controlled to capture an image of the molten pool from a position relative to the welding torch that is opposite to the predetermined direction. When the welding robot is turned around and moves in a direction opposite to the predetermined direction, the predetermined direction camera is controlled so as to capture an image of the molten pool from a position relative to the welding torch on the side of the predetermined direction. The welding system according to any one of claims 1 to 5.

7. A change means for changing a state of the welding robot based on the symptom information output by the output means; Further comprising: The state includes a tilt angle of a welding torch of the welding robot with respect to the predetermined direction and / or a speed at which the welding robot feeds a wire, When the output means outputs the symptom information, the change means changes the inclination angle so that the tip of the welding torch moves to the side of the moving direction of the welding robot or the side opposite to the moving direction, and / or increases or decreases the speed at which the welding robot feeds the wire. The welding system according to any one of claims 1 to 6.

8. the defect information includes occurrence information regarding the occurrence of the defect; The generation information is output by the output means based on a fact that a change in the length or the width measured by the measuring means exceeds a predetermined threshold. The welding system according to any one of claims 1 to 7.

9. a stop means for stopping the welding robot based on the generated information output by the output means; Further comprising: The welding system of claim 8 .

10. having a user select the predetermined threshold from among a first threshold, a second threshold, and a third threshold; 10. The welding system according to claim 8 or 9.

11. a storage control means for storing in a storage unit a log relating to a position of the welding robot when the output means outputs the defect information; Further comprising: The welding system according to any one of claims 1 to 10.

12. a storage control means for causing the output means to store in a storage unit information indicating which of the length or the width measured by the measuring means is based on which the output means outputs the defect information; Further comprising: The welding system according to any one of the preceding claims.

13. The measuring means measures the length or the width based on the luminance of the image data.

13. The welding system according to any one of the preceding claims.

14. A welding torch provided on the welding robot; Further comprising: The position of the welding torch is changed without changing the position of the imaging means.

14. The welding system according to any one of the preceding claims.

15. The steel material is a steel pipe having a curved portion.

15. The welding system according to any one of the preceding claims.

16. the defect is drooling of the molten pool or humping of the weld bead; 16. The welding system of claim 1 .

Images