Welding control apparatus and welding control method

Abstract

To provide a welding control apparatus and a welding control method capable of achieving welding in which positions of an electrode and a wire with respect to an edge of a bead of a preceding layer are properly maintained by detecting the edge of the weld bead of a welding object more stably than before.SOLUTION: A welding control apparatus includes: imaging means 10 that captures an image of an area including an area of a workpiece 3 to be welded during welding; and a processing unit 11 that controls the position of at least one of positions of an electrode 2 and a wire 5 on the basis of a boundary 64 between a weld bead 8 and a front layer bead 9 extracted from a welding image 51 during welding captured by the imaging means 10, where the processing unit 11 calculates the boundary 64 between the weld bead 8 and the front layer bead 9 from a time series image 52 in which areas away from a molten pool 7 are arranged in order in time series from a plurality of welding images 51 captured at different photographed time, and calculates the amount of movement of the boundary 64 between the weld bead 8 and the front layer bead 9 after certain time has elapsed from the calculated boundary 64 between the weld bead 8 and the front layer bead 9.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a welding control device and a welding control method.

Background Art

[0002] As an example of a welding control device that controls welding work on a welding object according to the posture of an electrode and the shape of the welding object, Patent Document 1 discloses a welding control device configured to control a position control target including at least one of a welding wire used for welding a welding object or an electrode for melting the welding wire. The welding control device includes a first determination unit configured to determine an actual position of the position control target based on a welding feature amount detected from an image captured so as to include at least the position control target, the welding feature amount including at least one of a wire position of the welding wire or an electrode position of the electrode; a second determination unit configured to determine a target position that is a target of the actual position according to input conditions based on at least one of posture information of the electrode or shape information of the welding object when welding the welding object; and a control unit configured to execute position control of the position control target to make the actual position the target position.

[0003] As an example of a welding device that predicts the occurrence of a welding defect based on the three-dimensional shape of a molten pool, the position within the groove of the molten pool, and the moving direction, and changes welding conditions to prevent the occurrence of a welding defect, Patent Document 2 discloses an imaging of a molten pool formed by a welding torch within a groove of a member to be welded and the groove shape in front thereof, obtaining the shape, moving direction, and moving speed of the molten pool, obtaining the coordinates of points on the joining edges between both ends in the width direction of the weld bead and the groove surface at a position immediately in front of the front in the advancing direction of the molten pool, predicting whether points are included in the region of the molten pool after t hours predicted from the distance and moving speed with substantially uniform penetration depth without deviation, and determining the presence or absence of the occurrence of a welding defect.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] For improving the efficiency and quality of arc welding, various proposals have been made for devices that automate welding control. For example, the techniques disclosed in Patent Document 1 and Patent Document 2 are known.

[0006] In automatic TIG welding in which a non-consumable electrode is used while continuously supplying a welding wire to a molten pool, the positions of the electrode and the wire deviate from an appropriate molten state due to fluctuations in welding conditions, so an operator needs to monitor and adjust them.

[0007] Particularly, in multi-layer welding in which a plurality of layers of welding beads are stacked and welded, it is important to properly maintain the positions of the electrode and the wire so as to completely melt the edge of the previous layer bead.

[0008] The edge of the previous layer bead has a convex shape, and the distance between the edge of the previous layer bead and the molten pool changes due to local shape changes, and the molten state may fluctuate. Therefore, the operator monitors the positions of the electrode and the wire with respect to the edge of the previous layer bead, and when it deviates from the appropriate position, an intervention operation for adjustment is performed. In order to automate such position adjustment work of the electrode and the wire and reduce the burden on the operator, a method for automatically detecting the position of the edge of the previous layer bead is required.

[0009] The device disclosed in Patent Document 1 can automatically perform arc welding with the same welding quality as that performed by a welder by determining the target positions of the electrode and the wire to be position-controlled based on the groove position or the molten pool position of the welding object obtained by image processing. However, there is a problem that there is no description regarding multi-layer welding, and it is difficult to stably detect the edge of the previous layer bead having a more complex shape than the groove.

[0010] The device disclosed in Patent Document 2 determines the coordinates of points on both edges in the width direction of the weld bead at a position in front of the advancing direction of the molten pool, predicts whether it will be included in the molten pool after a predetermined time through predictive calculation, and controls the welding conditions. However, since the brightness of the image acquired during welding decreases due to the filter that suppresses the arc light, the image becomes unclear at the position in front of the advancing direction of the molten pool, and there has been a problem that it is difficult to stably detect the edge of the previous layer bead.

[0011] Therefore, the present invention provides a welding control device and a welding control method capable of realizing welding in which the positions of the electrode and the wire with respect to the edge of the previous layer bead are properly maintained by stably detecting the edge of the weld bead of the welding object compared to the prior art.

Means for Solving the Problems

[0012] The present invention includes a plurality of means for solving the above problems. For example, an imaging unit that images an area including the area during welding of the material to be welded, and a processing unit that controls the position of at least one of the electrode and the wire based on the feature amount extracted from the captured image during welding captured by the imaging unit. The processing unit calculates the feature amount from a time-series image in which areas away from the molten pool are arranged in chronological order from a plurality of welding images with different imaging times, and calculates the feature amount movement amount after a certain time has elapsed from the calculated feature amount.

Effects of the Invention

[0013] According to the present invention, by stably detecting the edge of the weld bead of the welding object compared to the prior art, it is possible to realize welding in which the positions of the electrode and the wire with respect to the edge of the previous layer bead are properly maintained. Problems, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0015] Examples of the welding control device and the welding control method of the present invention will be described below with reference to the drawings. In the drawings used in this specification, the same or corresponding components are denoted by the same or similar reference numerals, and repeated explanations of these components may be omitted.

[0016] <Example 1> Example 1 of the welding control device and the welding control method of the present invention will be described with reference to FIGS. 1 to 4. FIG. 1 is a diagram showing an overview of TIG welding including the welding control device according to Example 1, FIG. 2 is a schematic diagram of multi-layer build-up welding, FIG. 3 is a schematic diagram of an image capturing a welding electrode, a molten pool, and a welding wire, and FIG. 4 is a diagram for explaining the processing drawing in the welding control device according to Example 1.

[0017] This example targets TIG (Tungsten Inert Gas) welding. TIG welding is a method in which an arc is generated between a tungsten electrode held by a welding torch and a base material, and the surrounding is wrapped with an inert gas such as argon, and welding is performed while supplying a welding wire as a filler material. The welding wire may be energized to generate Joule heat to form hot wire TIG welding. In hot wire TIG welding, the amount of wire deposition can be increased by supplying a high-temperature welding wire into the molten pool.

[0018] First, the state of the automatic TIG welding of the material to be welded 3 will be described with reference to FIG. 1. Although the welding machine is omitted in FIG. 1, the welding machine supplies power for generating an arc to the welding torch 1.

[0019] The arc is struck between the electrode 2 of the welding torch 1 and the material to be welded 3. The wire 5 is fed from in front of the welding torch 1. The wire 5 is melted by the arc and transferred to the base material. A molten pool 7 is generated directly below the electrode 2, forming a weld bead 8.

[0020] In the second layer and subsequent layers of multi-layer welding, welding is performed by overlapping on the previous layer bead 9.

[0021] FIG. 2 is a schematic diagram of multi-layer build-up welding. In multi-layer build-up welding, the weld bead 8 is overlapped on the previous layer bead 9. At this time, in order to prevent lack of fusion from occurring, it is necessary to adjust the position of either one or both of the electrode 2 and the wire 5 to an appropriate position so that the edge of the previous layer bead 9 is completely melted.

[0022] Returning to FIG. 1, the relative position with the material to be welded 3 can be changed by mounting the welding torch 1 on a moving carriage or combining it with a turntable fixed to a torch stand. The wire 5 is automatically supplied by a wire supply device 6. Photographing means 10 is installed between the welding torch 1 and the wire supply device 6.

[0023] Immediately before welding starts, the welder sets the welding torch 1 at the welding start position. Immediately after welding starts, the welder adjusts the feeding position of the wire 5 by the wire drive mechanism 12 so that the wire 5 is stably fed into the molten pool 7. After the welding operation stabilizes, the welder switches the wire drive mechanism 12 to the automatic monitoring mode and performs welding. It is also possible to switch from the automatic monitoring mode to the manual welding mode during welding.

[0024] In FIG. 1, the welding control device 100 is composed of photographing means 10 and a processing unit 11.

[0025] The photographing means 10 is composed of a camera for photographing an image of an area including the area during welding of the workpieces to be welded 3. Preferably, this photographing means serves as the execution entity of a photographing step for photographing an image of an area including the area during welding of the workpieces to be welded.

[0026] For example, the photographing means 10 is an optical camera such as a digital camera. Since high-intensity light is emitted from the location where the arc is struck during welding, it is necessary to select an optimal measuring device according to the operation of the welding work and the measurement target such as the welding phenomenon. Considering the characteristics of the arc light, it is desirable to use a camera equipped with a sensor that can receive light from the visible light region to the infrared region wavelength. Also, in order to prevent the occurrence of halation where the luminance in the image is saturated by the arc light, it is desirable to use a camera with a large dynamic range and adjustable exposure.

[0027] Also, it is desirable for the photographing means 10 to be provided with a light-shielding filter in order to suppress the influence of the strong light of the welding arc to a certain extent. The light-shielding filter may be made movable and interlocked with the presence or absence of the welding arc.

[0028] The processing unit 11 is an arithmetic processing device that controls the position of one or both of the electrode 2 and the wire 5 based on the boundary 64 (see FIGS. 3 and 4) between the weld bead 8 and the previous layer bead 9 extracted from the in-welding photographed image (hereinafter referred to as the welding image 51, see FIG. 3) photographed by the photographing means 10. Preferably, it serves as the execution entity of a processing step for controlling the position of one or both of the electrode and the wire based on the feature amount extracted from the in-welding photographed image photographed in the photographing step.

[0029] In this processing unit 11, from a time-series image 52 (see FIG. 3) in which regions away from the molten pool 7 are arranged in chronological order from a plurality of welding images 51 with different shooting times acquired by the shooting means 10, a boundary 64 between the weld bead 8 and the previous layer bead 9 is calculated as a feature amount. Further, a movement amount of the boundary 64 between the weld bead 8 and the previous layer bead 9 after a lapse of a certain time is calculated from the calculated feature amount (the boundary 64 between the weld bead 8 and the previous layer bead 9). Then, a position of one or more of the electrode 2 and the wire 5 that are control targets is determined and input to the wire driving mechanism 12.

[0030] Here, it is desirable that the processing unit 11 estimates a movement amount of the boundary 64 between the weld bead 8 and the previous layer bead 9 after a lapse of a certain time based on the position of the boundary 64 between the weld bead 8 and the previous layer bead 9 in a plurality of welding images 51 with different shooting times. Details thereof will be described later.

[0031] The wire driving mechanism 12 transmits a control signal for controlling the position of the electrode 2 or the wire 5 determined by the processing unit 11 to the driving unit of the electrode 2 or the wire 5 and drives the electrode 2 or the wire 5.

[0032] FIG. 3 is a schematic diagram of an image obtained by the shooting means 10 shooting the electrode 2, the molten pool 7, and the wire 5. The processing unit 11 extracts the tip position 61 of the electrode 2, the tip position 62 of the wire 5, and the edge position 63 of the previous layer bead 9.

[0033] Here, since there is halation due to the arc at the tip position 61 of the electrode 2, it is difficult to directly detect it from the welding image 51, but it can be estimated from the feature points 61a, 61b, 61c, 61d of the electrode 2. At the same time, the edge position 63 of the previous layer bead 9 and the position of the boundary 64 between the weld bead 8 and the previous layer bead 9 are detected.

[0034] The processing unit 11 calculates the deviation amount between the tip position 61 of the electrode 2 and the tip position 62 of the wire 5, the deviation amount between the tip position 61 of the electrode 2 and the edge position 63 of the previous layer bead 9, the deviation amount between the tip position 61 of the electrode 2 and the boundary 64 between the weld bead 8 and the previous layer bead 9, and the width of the weld bead 8. Based on these feature amounts, the processing unit 11 determines the positions of the electrode 2 and the wire 5 to be controlled. For example, when the deviation amount between the tip position 61 of the electrode 2 and the edge position 63 of the previous layer bead 9 deviates from the target range, the position of one or both of the electrode 2 and the wire 5 is changed so that the deviation amount approaches the target value.

[0035] The method for extracting the edge position 63 of the previous layer bead 9 will be described with reference to FIG. 4. In this example, in order to calculate the position of the edge position 63 of the previous layer bead 9 at time T, N + 1 images taken before time T at time intervals ΔT are used.

[0036] In each image from time T - NΔT to time T, an extraction region 53 that is in front of the welding direction from the molten pool 7 and is separated from the molten pool is cut out. In this way, the region separated from the molten pool 7 can be the region on the front side in the welding progress direction.

[0037] Next, a time-series image 52 in which the pixels of the extraction region 53 are arranged in time-series order is generated. The time-series image 52 is an image in which spatially continuous pixels of the image are arranged in time-series order. Therefore, the horizontal direction of the time-series image 52 represents spatial continuity, and the vertical direction represents temporal continuity.

[0038] First, the processing unit 11 performs image analysis on the previously generated time-series image 52 to detect the edge position 63 of the previous layer bead 9 at time T. Also, the boundary 64 between the weld bead 8 and the previous layer bead 9 is detected from this time-series image 52.

[0039] Furthermore, the processing unit 11 obtains parameters of a wire supply device 6, a moving carriage, a turntable, etc. for adjusting the position of either or both of the electrode 2 and the wire 5 to an appropriate position so that the detected boundary 64 between the weld bead 8 and the previous layer bead 9 completely melts, and outputs them to the wire drive mechanism 12.

[0040] Next, the effects of this embodiment will be described.

[0041] The welding control device 100 of Embodiment 1 of the present invention described above includes a photographing means 10 for photographing an image of a region including the region being welded of the workpiece 3, and a weld bead 8 and a boundary 64 between the weld bead 8 and the previous layer bead 9 extracted from the photographed image during welding by the photographing means 10. And a processing unit 11 that controls the position of one or more of the positions of the electrode 2 and the wire 5. The processing unit 11 calculates the boundary 64 between the weld bead 8 and the previous layer bead 9 from a time-series image 52 in which regions separated from the molten pool 7 are arranged in chronological order from a plurality of welding images 51 with different photographing times, and the calculated weld bead 8 and the previous layer bead 9. The amount of movement of the boundary 64 between the weld bead 8 and the previous layer bead 9 after a certain period of time is calculated from the boundary 64.

[0042] As a result, the edge of the previous layer bead 9 in multi-layer welding can be detected more stably than in the conventional method, so that deviation from an appropriate construction condition range (a condition for completely melting the boundary 64 between the weld bead 8 and the previous layer bead 9) is extremely small compared to the conventional method. High-precision welding can be realized. That is, according to the welding control device according to the present invention, it is possible to stably detect the edge of the previous layer bead 9 in multi-layer welding and realize welding without deviation from an appropriate construction condition range.

[0043] Further, since the processing unit 11 estimates the amount of movement of the boundary 64 between the weld bead 8 and the previous layer bead 9 after a certain period of time based on the position of the boundary 64 between the weld bead 8 and the previous layer bead 9 in a plurality of welding images 51 with different photographing times, the boundary 64 between the weld bead 8 and the previous layer bead 9 can be detected with higher accuracy.

[0044] Furthermore, by setting the region away from the molten pool 7 as the region on the front side in the welding progress direction, the boundary 64 between the weld bead 8 and the previous layer bead 9 at the location to be welded soon can be detected.

[0045] <Example 2> The welding control apparatus and method according to Embodiment 2 of the present invention will be described with reference to FIG. 5. FIG. 5 is a diagram showing an overview of TIG welding including the welding control apparatus according to Embodiment 2.

[0046] The welding control apparatus 100A of the present embodiment shown in FIG. 5 further includes a position acquisition unit 13 that acquires position information of one or more of the workpieces 3 and the imaging means 10 in addition to the configuration (imaging means 10, processing unit 11A) of the welding control apparatus 100 of Embodiment 1.

[0047] The position acquisition unit 13 is, for example, an encoder installed in a motor that drives the workpieces 3 or the imaging means 10. Further, the position acquisition unit 13 may be a displacement sensor such as a laser displacement meter installed on the workpieces 3 or the imaging means 10.

[0048] In addition, the processing unit 11A calculates the movement amount of the boundary 64 between the weld bead 8 and the previous layer bead 9 after a certain period of time based on the position information acquired by the position acquisition unit 13.

[0049] When the workpieces 3 or the imaging means 10 move during welding, the relative position between the workpieces 3 and the imaging means 10 changes. Accordingly, the position of the feature amount of the welding image 51 also changes. Therefore, it is difficult to distinguish whether the change in the feature amount detected from the welding image 51 is caused by the movement of the electrode 2 and the wire 5 or the movement of the workpieces 3 or the imaging means 10.

[0050] Therefore, the processing unit 11A of the welding control apparatus 100A calculates the movement amount of the feature amount after a certain period of time based on the position information of the workpieces 3 or the imaging means 10 acquired by the position acquisition unit 13.

[0051] The other configurations and operations are substantially the same as those of the welding control apparatus and the welding control method of Embodiment 1 described above, and the details are omitted.

[0052] In the welding control apparatus and the welding control method according to Embodiment 2 of the present invention, substantially the same effects as those of the welding control apparatus and the welding control method of Embodiment 1 described above can be obtained.

[0053] Further, it further includes a position acquisition unit 13 that acquires position information of one or more of the photographing means 10 and the work piece 3 to be welded. The processing unit 11A calculates the movement amount of the boundary 64 between the weld bead 8 and the previous layer bead 9 after a certain period of time based on the position information acquired by the position acquisition unit 13. When the position of the work piece 3 or the photographing means 10 is displaced, the position information of the work piece 3 or the photographing means 10 acquired by the position acquisition unit 13 changes, so that the movement of the work piece 3 or the photographing means 10 can be detected. Therefore, even when the work piece 3 or the photographing means 10 moves, the positions of the electrode 2, the wire 5, and the edge of the previous layer bead 9 can be detected with high precision and stability, so that welding without deviation from the appropriate construction condition range can be realized.

[0054] <Others> Note that the present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Also, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Also, it is possible to add, delete, or replace other configurations for a part of the configuration of each embodiment.

[0055] Also, each of the above configurations, functions, processing units, processing means, etc. may be realized in hardware by designing a part or all of them, for example, by an integrated circuit. Further, each of the above configurations, functions, etc. may be realized in software by a processor interpreting and executing a program for realizing each function. Information such as a program, a table, and a file for realizing each function can be placed in a memory, a recording device such as a hard disk or an SSD (Solid State Drive), or a recording medium such as an IC (Integrated Circuit) card, an SD card, or a DVD (Digital Versatile Disc).

[0056] In addition, the control lines and information lines show those considered necessary for explanation, and not all control lines and information lines are necessarily shown on the product. In fact, it may be considered that almost all components are interconnected.

Explanation of Signs

[0057] 1... Welding torch 2... Electrode 3... Workpiece to be welded 5... Wire 6... Wire feeding device 7... Molten pool 8... Weld bead 9... Previous layer bead 10... Imaging means (imaging unit) 11, 11A... Processing unit 12... Wire drive mechanism 13... Position acquisition unit 17... Wall surface of the workpiece to be welded 51... Weld image (captured image) 52... Time-series image 53... Extraction region 61... Tip position 61a, 61b, 61c, 61d... Feature points 62... Tip position 63... Edge position 64... Boundary (feature quantity) 100, 100A... Welding control device

Claims

1. An imaging unit that captures an image of a region including a region during welding of a workpiece to be welded; A processing unit that controls the position of one or more of the positions of the electrode and the wire based on a feature amount extracted from a captured image during welding captured by the imaging unit; and The processing unit calculates a feature amount from a time-series image in which regions separated from the molten pool are arranged in time-series order from a plurality of welding images with different imaging times, and calculates a feature amount movement amount after a lapse of a certain time from the calculated feature amount A welding control device.

2. In the welding control device according to claim 1, The processing unit estimates a feature amount movement amount after a lapse of a certain time based on the position of the feature amount in a plurality of welding images with different imaging times. A welding control device.

3. In the welding control device according to claim 1, Further provided with a position acquisition unit that acquires position information of one or more of the imaging unit and the workpiece to be welded, The processing unit calculates a feature amount movement amount after a lapse of a certain time based on the position information acquired by the position acquisition unit. A welding control device.

4. In the welding control device according to claim 1, The region separated from the molten pool is defined as a region on the front side in the welding progress direction. A welding control device.

5. An imaging step of capturing an image of a region including a region during welding of a workpiece to be welded; A processing step of controlling the position of one or more of the positions of the electrode and the wire based on a feature amount extracted from a captured image during welding captured in the imaging step; and In the processing step, a feature amount is calculated from a time-series image in which regions separated from the molten pool are arranged in time-series order from a plurality of welding images with different imaging times, and a feature amount movement amount after a lapse of a certain time is calculated from the calculated feature amount Welding control method.

Images