JP2001025867A - Method and equipment for controlling penetration weld - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a penetration weld state in welding and to control the welding condition based on a detected result. SOLUTION: When members 10, 12 to be welded are welded along a welding line Q by a welding electrode 14, a fused pool 22 on the back side is irradiated with a laser beam from a laser beam projector 28, a reflection beam of the laser beam is image picked up through an interference filter 32 by a CCD camera 34, the image picked up is processed by an image processor 46, width, length and area as a shape feature quantity of the fused pool 22 are detected, based on the detection result, the welding condition of a welding current, arc voltage, etc., are controlled by an overall controller 48.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for controlling uranami welding, and more particularly, to uranami welding on the reverse side of a groove-welded portion of a member to be welded which is opposite to the surface facing the welding electrode. An image of the state, processing of the Uranami image obtained by this imaging, and a Uranami welding control method suitable for controlling welding conditions such that an appropriate Uranami bead shape is obtained based on the processing result, and Related to the device.

[0002]

2. Description of the Related Art Conventionally, the state of welding of a member to be welded is monitored by a camera, for example, as disclosed in Japanese Patent Application Laid-Open No. 8-150475.
What is described in the gazette is known. In the invention described in this publication, when monitoring the welding condition of the member to be welded with a camera, in order to clearly capture the state of the molten pool, arc, and groove, the center wavelength is set to 600 to 800 nm, and 100 nm or less. An interference filter that transmits light with a wavelength in the range of 配置 is placed on the front of the CCD camera, and the optimal shutter speed is set according to each object such as molten pool, arc, groove, etc., and according to the set shutter speed Each object is imaged as a subject, and the image information of the arc, the molten pool, and the groove by this imaging is combined with the mask position of the screen set in the image processing apparatus in advance, and the image of each object is output to the monitor. Therefore, a method of displaying the image of each object clearly and controlling the welding conditions including the groove line profiling is adopted.

In the above-mentioned prior art, each object is imaged at an optimum shutter speed suitable for each object, and the arc, the molten pool, the image information in the groove, and the mask position of the screen set in the image processing apparatus are obtained by this imaging. Are synthesized and output to the monitor, so that the images are not synchronized in time, and only one image can be clearly displayed on the cut-out mask screen. Moreover, since each mask screen is displayed as a discontinuous image in the vertical direction of the screen, a clear image is not always obtained. Furthermore, since the images of the arc and the molten pool on the front side are taken in and processed, it is not possible to directly monitor the state of penetration (reverse welding state) on the back side of the groove.

[0004] In the welding operation at the butt groove, the member to be welded is divided into several layers from the front side (the side facing the welding electrode) and overlapped. In the first layer welding at this time, welding cannot be performed from the back side of the member to be welded,
When welding from the front side of the member to be welded, since the melting state of the back side is not known, the Uranami weld bead melts down,
Alternatively, poor fusion may occur due to insufficient penetration. The quality of the backside bead of the first layer welding is an important point that determines the welding quality, but in the first layer welding from the front side, without knowing the melting state of the back side, a good Obtaining a Uranami bead is very difficult even for a skilled welder.

In order to monitor the welding condition on the back side of the member to be welded with a camera, see, for example, Japanese Patent Application Laid-Open No. 7-214.
The one described in Japanese Patent Publication No. 316 is proposed.
According to the invention described in this publication, when welding is performed from the front side of the member to be welded, a laser slit light of a parallel light beam is irradiated to the welding line of the member to be welded from the back side of the member to be welded, The reflected laser slit light is captured by a camera via an interference filter, and an image of the Uranami bead is captured by the camera.The image obtained by this imaging is processed by an image processing device to determine the height of the Uranami bead. A method is employed in which welding conditions are controlled by a single-sided welding control device according to the wave bead height and the welding position.

[0006]

When monitoring the state of backside welding of a member to be welded with a camera, the state of formation of the backside bead immediately after welding is monitored by a light cut image, so that the result of the weld bead is good. The evil can be determined. However, judging the formation state of the Uranami bead immediately after welding means that the result after welding is determined to the last, and even if the welding conditions are controlled for those already having a defective Uranami bead. It cannot be recovered.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and an apparatus for controlling a backside welding capable of detecting a backside welding state during welding and controlling welding conditions in accordance with the detection result.

[0008]

In order to achieve the above object, the present invention relates to a groove welding portion in which a plurality of members to be welded come into contact with each other and are melted by the welding electrode. Captures an image of the molten pool on the opposite side as a subject, processes the image of the molten pool by this imaging, extracts the shape characteristic amount of the molten pool, and controls welding conditions based on the shape characteristic amount. This adopts a wave welding control method.

[0009] When the backside welding control method is adopted, when the molten pool behind the groove fusion zone is imaged as a subject, light can be applied to the fusion pool behind the groove fusion zone.

[0010] The present invention is also directed to a molten pool on a back side of a groove fusion zone where a plurality of members to be welded come into contact with each other and are melted by a welding electrode, which is opposite to a surface facing the welding electrode. An imaging unit for imaging, a shape feature amount extraction unit for processing an image of the molten pool by the imaging by the imaging unit to extract a shape feature amount of the molten pool, and a shape feature amount extracted by the shape feature amount extraction unit. And a welding condition control means for controlling welding conditions based on the welding conditions.

[0011] In configuring the Uranami welding control device, a plurality of members to be welded come into contact with each other and are melted by the welding electrode. Irradiation means for irradiating the molten pool with light can be provided.

The following elements can be added when configuring each of the above Uranami welding control devices.

(1) A moving means for moving the irradiation means and the imaging means in accordance with a movement command along a welding line where the plurality of members to be contacted with each other, and processing an image of the molten pool by the imaging means. Position detecting means for detecting the center position of the image of the molten pool, display means for displaying an image of the molten pool obtained by the imaging means, and a display value of the detected value of the position detecting means and the display image of the display means A deviation calculating means for calculating a deviation from the center position, and a movement command means for outputting to the moving means a movement command for suppressing the deviation calculated by the deviation calculating means to zero.

(2) The irradiating means is constituted by a laser projecting means for irradiating the molten pool with laser light, and the imaging means images the molten pool through an interference filter which transmits only the laser light. Become.

(3) The laser projecting means includes: a laser oscillator that oscillates a laser beam; an optical fiber that transmits the laser beam from the laser oscillator; and a laser beam that is transmitted by the optical fiber and directed to the melting pool. And a laser projector for performing irradiation.

(4) The laser projector is provided with a semiconductor laser diode.

(5) A beam shaping plate is arranged in a transmission path of the laser beam irradiated from the laser projecting means toward the melting pool.

(6) The shape feature quantity extracting means extracts any one of the width, length and area of the molten pool as a shape feature quantity of the molten pool.

According to the above-mentioned means, the image of the molten pool is processed to extract the shape characteristics of the molten pool, for example, the length, width and area of the molten pool, and the welding conditions, For example, it is possible to control a welding current, an arc voltage, and the like. Detects the state of the molten pool during welding,
By controlling the welding conditions according to this detection result,
A stable Uranami bead can be obtained, which can contribute to improvement in welding quality.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of a welding system that employs a Uranami welding control device according to the present invention. In FIG. 1, the members to be welded 10 and 12 are formed in a cylindrical shape, and the axial end surfaces of the members to be welded 10 and 12 are grooved. Each of the members to be welded 10, 12
Are arranged in a state of being overlapped with each other in a state where the end faces in the axial direction are in contact with each other. The line where the members to be welded 10 and 12 are in contact with each other is set as a welding line Q, and a welding electrode 14 is arranged on the surface side of the members to be welded 10 and 12. This welding electrode 14 is an electrode position driving unit 1
6 and are arranged integrally. Electrode position driver 16
Travels on a traveling axis (not shown) attached in parallel to the welding line Q on the outer periphery of the workpiece 10 or 12 in response to a signal from the electrode position control device 20. The traveling of the electrode position drive unit 16 allows the welding electrode 14 to move along the welding line Q and to move in two directions orthogonal to the welding line Q. The welding by the welding electrode 14 is performed according to the arc voltage and the welding current from the welding power source 18,
12, the groove portions of the members to be welded 10 and 12 are melted, and a molten pool 22 is formed on the back side of the melted portion opposite to the surface facing the welding electrode 14. Has become. At this time, the welding state on the front side of the members to be welded 10, 12, ie, the arc state, is imaged by an ITV camera, for example, a CCD camera 24. That is, the CCD camera 24 includes the filter 26
, An optical signal indicating the state of the front side of the members to be welded 10 and 12 is input, and an image captured by the CCD camera 24 is displayed on the screen of the monitor TV 27. The CCD camera 24 can also move on the traveling axis in accordance with the movement of the welding electrode 14.

On the other hand, in order to monitor the state of reverse welding of the members 10 and 12 to be welded, a laser projector 28, a beam shaping plate 30, an interference filter 32, and an ITV camera are provided behind the members 10 and 12 to be welded. A CCD camera 34, a remote monitoring position drive unit 36, and the like are provided. The laser projector 28 is connected to a laser oscillator 40 via an optical fiber cable 38. The CCD camera 34 is connected to an overall control device 48 via an analog control circuit 42, a video distributor 44, and an image processing device 46. The remote monitoring position drive unit 36 is disposed integrally with the CCD camera 34,
It is connected to the overall control device 48 via the remote monitoring position control device 50.

The laser oscillator 40 is, for example, He-Ne
The laser oscillator 40 comprises a laser oscillator.
The laser beam generated by the oscillation is received by the laser projector 28 via the optical fiber cable 38. The laser projector 28 is configured to irradiate the received laser beam to a molten pool (melt pool) 22 via a beam shaping plate 30 made of, for example, frosted glass. That is, the laser oscillator 40, the optical fiber cable 38, and the laser projector 28 are configured as irradiation means, and the beam shaping plate 30 is arranged on the front side of the laser projector 28 so as to be integrated with the laser projector 28 (not shown). ing.
The laser projector 28 is provided with a lens system (not shown) for irradiating the molten pool 22 with the laser beam having an appropriate spread. Beam shaping plate 3
0 is provided to eliminate an image that is difficult to see due to a speckle pattern. That is, the beam shaping plate 30
When the reflected image obtained when the laser beam is directed toward the molten pool 22 without inserting the laser beam is captured by the CCD camera 34, the members to be welded (welded workpieces) 10 and 12 form random surface irregularities. Moreover, since the laser light is coherent (coherent) light, a speckle pattern usually called a speckle pattern is observed. This phenomenon is due to an interference phenomenon that occurs when coherent irradiation light is randomly diffused by a diffusion object on the surface of the welding work and scattered waves from each point are superimposed on each point on the observation surface. At this time, the speckle pattern image observed by the CCD camera 34 is very difficult to see due to an infinite number of spots that partially shine. However, when the laser beam is applied to the molten pool 22 via the beam shaping plate 30, an image which is difficult to see due to the speckle pattern can be eliminated.

The interference filter 32 is configured as a filter that transmits only the laser light emitted from the laser projector 28, and is arranged on the front side of the CCD camera 34 integrally with the CCD camera 34. CCD camera 3
4 and the laser projector 28 are disposed integrally with the remote monitoring position driving unit 36, and the remote monitoring position driving unit 36
In response to a signal from the remote monitoring position control device 50, it can be moved in two directions orthogonal to the welding line Q. Further, it can travel on a traveling shaft (not shown) attached to the inner periphery of the workpiece 10 or 12 in parallel with the welding line Q. The CCD camera 34 is configured as an imaging unit or a two-dimensional light receiving unit that captures the laser light from the molten pool 22 via the interference filter 32 and captures an image of the molten pool 22 as a subject.
The analog video signal obtained by the imaging by the CD camera 34 is input to the image processing device 46 via the control circuit 42 and the video distributor 44. In this case, the analog video signal generated by the control circuit 42 is divided into two analog video signals by the video distributor 44, one of the analog video signals is input to the monitor TV 52, and the other analog video signal is output to the image processing device 46. Is to be processed. Then, the image processed by the image processing device 46 is displayed on the monitor TV5.
4 is displayed on the screen. in this case,
On the screen of the monitor TV 52, as shown in FIG.
As an image captured by the D camera 34, a molten pool image P
Is displayed, and the surrounding groove image K and the molten pool 2 are displayed.
The molten bead image B after the solidification of No. 2 is displayed. In addition,
X and Y in FIG. 2 indicate coordinate axes on the screen, respectively.

Here, in the present embodiment, when irradiating the light to the melting pool 22, a laser beam is used, and the reflected light by the laser beam is reflected by the CCD camera 34.
, And has the following characteristics.
That is, a major feature of laser light is that it has good monochromaticity. That is, the width of the oscillation frequency is extremely narrow. Therefore, when an image of the periphery of the molten pool 22 including the molten pool 22 is taken by the CCD camera 34 as a subject, an interference filter 32 having an extremely small transmission wavelength half width can be used. On the other hand, the interference filter 32
When the observation angle of the laser light incident on the front surface of the laser beam becomes smaller or larger around 90 degrees (perpendicular incidence), the wavelength of the transmission center shifts to the lower wavelength side due to the characteristics of the interference filter 32. That is, when the interference filter 32 is arranged in front of the CCD camera 34 and the molten pool 22 is imaged, the transmission center wavelength is different from that of the CCD camera 34 because the viewing angles of the incident images are different between the central part and the peripheral part of the screen. It differs slightly depending on the position of the element, that is, the position of the screen. in this case,
Considering that this effect does not occur at a desired observation viewing angle, an interference filter having a small transmission wavelength half width may be used. The magnitude of the half bandwidth of the transmission wavelength is preferably 5 nm or less. The narrower the half-width of the transmission wavelength, the lower the brightness of the high-intensity molten pool image P can be observed. That is, not only the molten pool image P but also a peripheral groove image K and a molten bead (solid phase) image B can be clearly captured. In FIG. 2, a horizontal stripe image is displayed as the peripheral groove image K. This image is due to the unevenness of the groove processing surface, and bright portions and dark portions alternately appear in the screen vertical direction. Is shown.

The image processing device 46 processes the image of the molten pool 22 in accordance with the analog video signal from the video distributor 44 and obtains the shape characteristic amount of the molten pool 22 as shown in FIG. Is configured as a shape feature quantity extracting means for extracting the width B, the length L, and the area S of the image. The image based on the processing result is displayed on the screen of the monitor TV 54 as a display means, and the processing result is displayed on the overall control device 48. Output. The overall control device 48 generates a control signal for controlling the welding conditions for the welding electrode 14 based on the shape characteristic amount obtained by the processing of the image processing device 46, and outputs the control signal to the welding power source 18. Is configured as
A signal for driving the electrode position driving unit 16 and the remote monitoring position driving unit 36 is generated, and this signal is output to the remote monitoring position control device 50 and the electrode position control device 20, respectively.

Here, in the present embodiment, the following is considered when controlling the welding conditions for the welding electrode 14. That is, the following relationship exists between the welding conditions and the shape of the molten pool 22.

(1) As the welding current increases, the width (length in the direction perpendicular to the welding direction) and length (length in the welding direction) of the molten pool 22 increase.

(2) When the arc voltage is reduced, the width B and the length L of the molten pool 22 are increased.

(3) The smaller the arc voltage is, the more the shape of the Uranami bead becomes convex.

(4) From the surface facing the welding electrode, the molten pool 2
When the feed speed of the welding wire (not shown) inserted into the second wire 2 is increased, the shape of the back bead becomes convex.

From the above, the molten state of the molten pool 22, that is, the shape information of the width B, the length L, and the area S of the molten pool 22 is monitored, and the arc voltage, the welding current, the welding speed, or the feeding of the welding wire are monitored. By controlling the feed rate,
It is possible to obtain an appropriate Uranami bead.

More specifically, as shown in FIG. 4, in response to an arc voltage command for forming a width B of the back side molten pool 22 at which a predetermined back side bead is appropriate, an actual molten pool width Bm is set. Is detected by the image processing device 46 and the molten pool 2 is detected.
The arc voltage by the welding power supply 18 is controlled based on the difference between the width target value Bc of No. 2 and the actual molten pool width Bm. In this case, for example, the width target value Bc of the molten pool 22 in the first-layer welding pass is set in the overall control device 48 by the operation of the operator 56 before the start of welding. Then, the comparator 58 of the overall control unit 48 compares the target width Bc of the molten pool 22 with the actual molten pool width Bm by the processing of the image processing unit 46, and compares the comparison result with the arc voltage correction amount command value generation unit 60. Output to Arc voltage correction amount command value generation unit 60
, An arc voltage correction amount command value corresponding to the difference between the target value Bc and the detected molten pool width Bm is set in advance, and the arc voltage correction amount command value corresponding to the comparison result of the comparator 58 is set to the welding value. The arc voltage is input to the power supply 18 and the arc voltage at the time of welding by the welding power supply 18 is corrected according to the arc voltage correction amount command value. In this case, the arc voltage correction amount command value is a constant ratio value that is sufficiently smaller than the arc voltage correction amount command value obtained from the difference between the target value Bc and the detected molten pool width Bm. 18 can also be controlled. At this time, the value of the fixed ratio can be freely changed from outside. In this case, the welding control can be performed in a stable state without suddenly changing the arc voltage.

The present invention is not limited to the case where the arc voltage is modified based on the molten pool width, but may be modified based on the length or area of the molten pool 22 instead of the molten pool width. Can also. By performing such control, it is possible to set and control extremely fine welding conditions. Further, the target width Bc of the molten pool may be independently set in advance for each welding position such as a welding position or a downward, upward, downward or upward welding position in welding.

Next, the processing for extracting the shape feature amount of the molten pool image will be described with reference to the flowchart of FIG. First, the image of the melting pool 22 is taken into the image processing device 46 by the imaging of the CCD camera 34 (step S1). Thereafter, processing for removing unnecessary images from the input image is performed (step S2). At this time, in the present embodiment, differentiation processing is performed on the pixels in the vertical direction among the pixels constituting the screen shown in FIG. In this case, the original image is a two-dimensional array of luminance,
If this is represented as F (Xi, Yi), F (Xi, Yi)
(i, Yi) represents the pixel (Xi, Yi) of the image F, and represents the luminance at that point. Then, differential processing is sequentially performed on luminance data obtained from pixels adjacent to each other along the vertical direction of the screen, and an image after the differential processing is represented by G (Xi, Yi). The processed image is represented by the following equation.

[0035]

(Equation 1)

Here, when the luminance data along the line aa 'in FIG. 3 is extracted, an image as shown in FIG. 6 is displayed. In this case, the range of Y2 is molten pool 2
2, Y1 represents the luminance characteristic of the groove portion above the molten pool 22, and Y3 represents the luminance characteristic of the molten pool 22.
5 shows luminance characteristics of a groove portion below the groove. When this luminance data (luminance data along the line aa ′ in FIG. 3) is differentiated, as shown in FIG. 7, in the range of Y1 and Y3, a minimum value where the luminance changes from a low point to a high point is obtained. Conversely, a maximum value that changes from a point having a high luminance to a point having a low luminance is generated alternately. On the other hand, in the range of Y2, the brightness of the molten pool 22 shows a characteristic in which the brightness of adjacent pixels in the vertical direction does not change much.

When the luminance data along the line bb 'shown in FIG. 3 is differentiated, the characteristics shown in FIG. 8 are obtained.
In this case, the differential value of the surface of the molten bead is shown in the range of Y2, but has a characteristic that the fluctuation of the differential value is large due to unevenness of the surface of the weld bead. In this way, by differentiating the brightness data, an area where the variation of the differential value is small is set as the image of the molten pool 22, and the other area is set as a groove area around the weld bead or the molten pool. Only the image of the molten pool 22 can be cut out.

As described above, by utilizing the area having a small differential value in the vertical line on the screen as the molten pool 22, the differential value of the vertical line on the screen is shifted further in the horizontal direction, and the area other than the molten pool 22 is shifted. Unnecessary image is detected, and this image is removed. That is, the luminance is set to the 0 level.

Thereafter, the process proceeds to step S3, where a binarization process using the threshold value Ith is performed according to the following equation (2), and only the image of the molten pool 22 is cut out from the screen.

[0040]

(Equation 2)

Next, the cut-out image of the molten pool 22 is subjected to a process based on contraction and expansion, and a process for eliminating noise of small components, small holes, and the like is performed (step S4). This shrinkage is a process of reducing the size of one layer by removing a boundary point in a given range as shown in the following equation (3). As shown in the following equation (4), the expansion is 1
This is the process of thickening the layers. By performing the contraction processing and the expansion processing in combination, small components and small holes in the binarized image can be removed.

[0042]

(Equation 3)

[0043]

(Equation 4)

Next, in step S5, each coordinate position of the contour around the molten pool 22 is detected. That is, the position coordinates of the pixel indicating the outline of the molten pool 22 are detected. In this case, by the processing up to step S4, the portion of the molten pool 22 becomes white (level 1), and the outside of the molten pool 22 becomes black (level 0). Therefore, the image is searched from the outside in the horizontal or vertical direction, and from black (0 level) to white (1 level).
The contour position can be found by detecting a point that changes to (level).

Next, in step S6, the left and right boundary positions in the horizontal direction of the screen are detected from the outline coordinates of the molten pool 22 obtained in step S5. At this time, the left boundary is G1
(X1, y1), and the right boundary is G2 (x2, y2).

Next, in step S7, as in step S6, the upper and lower boundary positions in the vertical direction of the screen are detected from the outline coordinates of the molten pool 22 obtained in step S5. At this time, the upper boundary is G3 (x3, y3), and the lower boundary is G4 (x4, y4). Next, step S
8, the width B, the length L, and the center position G0 (x0, y) of the molten pool 22 are determined from the left and right boundary positions and the upper and lower boundary positions of the molten pool 22 obtained in Steps S6 and S7.
0) is calculated according to the following equations (5) to (7).

[0047]

(Equation 5)

[0048]

(Equation 6)

[0049]

(Equation 7)

The width B and length L of the molten pool 22 obtained by the above processing are values on the screen. Therefore, in step 9, the value on the screen is multiplied by the camera resolution (the size of the visual field per pixel) to convert it to an actual value. Thus, actual values can be obtained as the width and length of the molten pool 22.

Next, the welding condition control operation of the system shown in FIG. 1 will be described with reference to the flowchart of FIG. In this case, an image of the molten pool 22 is taken while the members to be welded 10 and 12 are being welded.
The case where the width of the welding is detected and the welding condition is controlled based on the detected information will be described. In this operation, the overall control device 48 becomes a master station for managing the operation of the entire system, and the welding power source 18, the electrode position control device 20, and the image processing device 46 are in a slave station relationship. That is, the slave power supply 18, the electrode position control device 20, and the image processing device 46
Performs a predetermined operation in response to a command from the overall control device 48, which is the master station.

More specifically, after the operation of the overall controller 48 starts, in step F1, the overall controller 48 first inquires the current position of the welding electrode 14 to the electrode position controller 20 and reports the position information. (Step F1
7). Next, in Step F2, the overall control device 48 issues a movement command for raising the welding electrode 14 to the electrode position control device 20, and separates the welding electrode 14 from the groove surface (Step F18).

In step F3, the overall control device 48 issues a movement command to the electrode position control device 20 to the reference position at which the welding electrode 14 starts welding, and moves the welding electrode 14 to the reference position (step F19). ). In step 4, a command to move the welding electrode 14 to a predetermined position where the welding electrode 14 can start an arc is issued to the overall control device 4.
8 is issued to the electrode position control device 20, and the welding electrode 1
4 is moved to a predetermined position where the arc can be started (step F20).

In step F5, the overall control device 48 issues an arc start (ON) command to the welding power source 18 to start the arc ON (step F22). In step 6, the general control device 48 issues a command to start the traveling of the welding electrode 14 in the direction of the welding line Q by the electrode position control device 20.
To start traveling in the Q direction (step F21). In the traveling operation in the Q direction, the traveling operation of the welding electrode 14 is continued until a traveling stop command described later is generated.

In step F7, the overall control device 48 issues a detection command to the image processing device 46, and the image processing device 46 detects the width of the molten pool 22 in the above-described processing (step F26). In step 8, the overall control device 48 inquires of the welding power supply 18 about the set arc voltage value and receives a report of the information (step F23).

In step 9, the overall control device 48 issues a report command to the image processing device 46 to receive the detection result of the width of the molten pool 22, and the image processing device 46 receives a report of the result ( Step F27). In step 10, the arc voltage information in step 8 and the detection result information on the molten pool width in step 9 are stored internally. Thereafter, a step F11 calculates an arc voltage correction amount according to a difference between the detection result of the molten pool width and the target value. Thereafter, in step F12, the information calculated in step F11 is transferred to the welding power source 18 to correct the arc voltage (step F24).

In step F13, it is determined whether or not the welding operation is at the end position based on the current position information of the welding electrode 14. If the position of the welding electrode 14 is still at the end position (the overall control device 4 is determined in advance).
If it is not the position determined and stored in step 8), the process returns to step F7, and the above operation is repeated.

On the other hand, when it is determined that the electrode position has exceeded the end position, the process proceeds to step F14. Step F1
At 4, the overall control device 48 issues an arc end (OFF) command to the welding power source 18 to stop the arc ON (step F27). Further, in step F15, the overall control device 48 issues a command to stop traveling in the Q direction to the electrode position control device 20, and stops traveling of the welding electrode 14.

In the above processing, the width of the molten pool 22 is detected and the arc voltage is controlled based on the detected information. However, in addition to the width of the molten pool 22, the length or area of the molten pool 22 is controlled. Can be used to control the arc voltage or the welding current.

The laser projector 28 and the CCD camera 34
Is moved in accordance with the state of welding by the welding electrode 14, the center position of the molten pool 22 is detected based on the shape characteristic amount of the molten pool 22, and the center position of the molten pool 22 and the center position of the image are determined. A deviation (deviation) is obtained, a movement command for suppressing the deviation to zero is generated, and the laser projector 28 and the CCD camera 34 are generated according to the movement command.
Can be moved along the welding line Q. In this case, in step F26 shown in FIG. 9, a deviation between the center position of the image of the molten pool 22 and the center position of the display image on the monitor TV 54 is obtained, and a movement command for suppressing this deviation to zero, that is, the molten pool Monitor T is at the center of 22
A movement command is generated so as to be at the center of the screen of V54, and the laser projector 28, CC
The movement of the D camera 34 is controlled. By performing such control, the image of the molten pool 22 is always displayed.
Is displayed such that the center of the screen is located at the center of the screen of the monitor TV 54. In this case, the image processing device 46 constitutes position detecting means for detecting the center position of the image of the molten pool, and the overall control device 48 calculates the deviation between the detected value of the position detecting means and the center position of the monitor TV 54 display image. And a movement command means for outputting a movement command for suppressing the deviation to zero to the moving means.

According to the present embodiment, since the welding conditions by the welding power source 18 are controlled based on the shape characteristic amount of the molten pool 22, a stable Uranami bead can be obtained, which contributes to the improvement of welding quality. can do.

Further, according to the present embodiment, a laser beam is applied to the melting pool 22, and the reflected light of the laser beam is applied to the CCD.
Since the image is taken by the camera 34, a good Uranami monitor image required for a remote welding operation can be obtained.
Further, a good monitor image in the vicinity of the welded portion can be obtained before or during welding without switching the interference filter 32 or switching the shutter speed of the CCD camera 34.

In the above embodiment, the irradiation light source is He-Ne.
Although a laser oscillator using a laser oscillator has been described, a laser oscillator using a semiconductor laser diode can also be used.

[0064]

As described above, according to the present invention,
Since the shape of the molten pool is extracted by processing the image of the molten pool and the welding conditions are controlled based on this shape feature, a stable Uranami bead can be obtained and the welding quality can be improved. It can contribute to improvement.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a welding system to which an apparatus according to an embodiment of the present invention is applied.

FIG. 2 is an explanatory diagram of a configuration of a molten pool image.

FIG. 3 is a diagram for explaining a shape characteristic amount of a molten pool.

FIG. 4 is a block diagram for explaining a method for controlling welding conditions.

FIG. 5 is a flowchart for describing a processing method for extracting a shape feature amount of a molten pool.

FIG. 6 is a schematic diagram of luminance along the line aa ′ in FIG. 3;

FIG. 7 is a schematic diagram when the luminance data shown in FIG. 6 is differentiated.

FIG. 8 is a schematic diagram when differentiating the luminance data along the line bb ′ in FIG. 3;

FIG. 9 is a flowchart for explaining a welding condition control operation of the system shown in FIG. 1;

[Explanation of symbols]

 10, 12 Welded member 14 Welding electrode 16 Electrode position drive unit 18 Welding power supply 20 Electrode position control device 22 Melting pool 24 CCD camera 28 Laser projector 30 Beam shaping plate 32 Interference filter 34 CCD camera 36 Remote monitoring position drive unit 38 Optical fiber Cable 40 Laser oscillator 46 Image processing device 48 Overall control device 50 Remote monitoring position control device

Continued on the front page (72) Inventor Mitsuaki Haneda 502, Kandachicho, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratory, Hitachi, Ltd. (72) Inventor Takeshi Wada 3-1-1 Sachimachi, Hitachi-shi, Ibaraki Hitachi Hitachi Works, Ltd. (72) Inventor Yasushi Tamai 3-1-1 Sachimachi, Hitachi-shi, Ibaraki Pref. Hitachi Works Hitachi Works

Claims (10)

[Claims] 1. An image of a molten pool on the back side of a groove fusion zone where a plurality of members to be welded come into contact with each other and are melted by a welding electrode, which is opposite to a surface facing the welding electrode, is imaged. A backside welding control method for processing an image of a molten pool by imaging to extract a shape characteristic amount of the molten pool and controlling welding conditions based on the shape characteristic amount. 2. A method in which a plurality of welded members are in contact with each other and irradiate light to a molten pool on a back side opposite to a surface facing the welding electrode in a groove melted portion melted by a welding electrode, An image of the molten pool on the back side of the groove fusion zone as a subject, processing the image of the molten pool by this imaging to extract the shape characteristic amount of the molten pool, and controlling welding conditions based on the shape characteristic amount. Wave welding control method. 3. An imaging means for imaging, as a subject, a molten pool on a back side of a groove fusion portion where a plurality of members to be welded come into contact with each other and are fused by a welding electrode, which is opposite to a surface facing the welding electrode. A shape feature extraction means for processing an image of the molten pool by the imaging means to extract the shape feature of the molten pool; and welding conditions based on the shape feature obtained by the extraction by the shape feature extraction means. Uranami welding control device comprising: welding condition control means for controlling the welding condition. 4. Irradiating means for irradiating light to a molten pool on the back side opposite to a surface facing the welding electrode in a groove fusion zone where a plurality of members to be welded come into contact with each other and are melted by the welding electrode. Imaging means for imaging the molten pool on the back side of the groove fusion part as a subject; and shape characteristic amount extracting means for processing an image of the molten pool by imaging with the imaging means to extract the shape characteristic amount of the molten pool; And a welding condition control means for controlling welding conditions based on the shape feature quantity extracted by the shape feature quantity extraction means. 5. A moving means for moving the irradiating means and the imaging means in accordance with a movement command along a welding line where the plurality of members to be contacted with each other, and processing an image of the molten pool by the imaging of the imaging means. Position detecting means for detecting the center position of the image of the molten pool, display means for displaying an image of the molten pool obtained by the imaging means, and the detected value of the position detecting means and the center of the display image of the display means. The apparatus according to claim 1, further comprising: deviation calculating means for calculating a deviation from the position; and movement command means for outputting a movement command to the moving means for suppressing the deviation calculated by the deviation calculating means to zero. Item 7. An underside welding control device according to Item 4. 6. The irradiating means is constituted by a laser projecting means for irradiating a laser beam to the molten pool, and the imaging means is configured to image the molten pool through an interference filter transmitting only the laser light. The Uranami welding control device according to claim 4 or 5, wherein: 7. The laser projecting means includes: a laser oscillator that oscillates a laser beam; an optical fiber that transmits a laser beam from the laser oscillator; and a laser beam that is transmitted by the optical fiber and directed to the melting pool. 7. A laser projector for irradiation.
Uranami welding control device as described. 8. The laser projector according to claim 7, wherein the laser projector includes a semiconductor laser diode.
Uranami welding control device as described. 9. The Uranami welding as claimed in claim 6, wherein a beam shaping plate is arranged in a transmission path of the laser beam irradiated from the laser projecting means toward the molten pool. Control device. 10. The method according to claim 3, wherein the shape characteristic amount extracting means extracts any one of a width, a length, and an area of the molten pool as a shape characteristic amount of the molten pool. Uranami welding control equipment.