JP2825414B2 - Arc welding imaging method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic welding machine for photographing an arc welding state with a television camera and performing a welding operation by remote control while observing a monitor television, or using an image signal of the television camera. Necessary to control the
The present invention relates to a method and an apparatus for photographing arc welding.

[0002]

2. Description of the Related Art In a normal arc welding, a welding operator is required to operate as shown in FIG.
Arc 49, molten pool 47, bead 4
8. The welding state is determined while observing the groove 46 and the like, and the welding control device is operated in accordance with this to perform appropriate welding. Also, when welding dangerous or narrow welding spots that cannot be directly observed or operated by the welding operator, the welding condition should be photographed with a TV camera, and the captured image should be observed remotely on a monitor TV. How to operate,
A method of automatically controlling a welding machine using an image signal of a television camera has been attempted.

In order to remotely control or automatically control arc welding by such a method, the arc 49, the molten pool 47, the bead 48, the groove 46, and the like must be photographed well. However, when the arc welding is photographed with a television camera, there are the following problems. That is, the arc light emits strong light, but the light from the molten pool, the bead, the groove, and the like is relatively dark, so that the intensity range of the actual incident light is wider than the appropriate sensitivity range of the television camera. For this reason, if the filter is deepened or the aperture is closed in order to satisfactorily shoot an arc having a high light intensity, it becomes impossible to satisfactorily shoot a molten pool, a bead, a groove, or the like having a low light intensity. On the other hand, if the filter is made thinner or the aperture is opened in order to photograph the molten pool, bead, groove, etc. better, arc light with high light intensity will be incident, and afterimages will appear around the arc, making it impossible to photograph well. Or the image sensor may be destroyed. Recently, even after shooting the intense light of arc welding, no residual image or destruction of the image sensor occurs.
Since a CD camera has been developed, it is possible to take an image of a welded portion by using this. However, even when such a CCD camera is used, afterimages and destruction of the image sensor do not occur even when the welded portion is photographed, but when an intense arc light is photographed, an image called a smear phenomenon is generated. White noise occurs in the vertical direction of the image. For this reason, a part of the molten pool, the bead, the groove, and the like may not be observed, and as a result, a welding operator may make an operation error or a malfunction may occur in automatic control by image signal processing.

[0004] In order to solve such a problem, a method of selectively dimming intense arc light of welding has been conventionally proposed. First, in Japanese Patent Publication No. 3-71220, the wavelength band where the spectrum of the arc light peaks is on the short wavelength side, and the wavelength band of the radiation spectrum of the molten pool is on the long wavelength side. Focusing on the fact that the difference in light intensity between the two becomes smaller, only the long wavelength band where the intensity of the arc light is not so much greater than the intensity of the light from the molten pool is selected using a filter or an infrared TV camera, and There has been proposed a method of taking an image by removing a short wavelength band other than the above. It is stated that this makes it possible to photograph the molten pool even with bright arc light.

In Japanese Patent Application Laid-Open No. 54-99754, the wavelength band where the spectrum of the arc light peaks is on the short wavelength side, and the wavelength band of the radiation spectrum of the molten pool is on the long wavelength side. Images are alternately taken by a television camera through a filter 1 that transmits light on the wavelength side or a filter 2 that transmits light on the long wavelength side, and the position and width of the groove and the position of the welding torch are determined from the image taken by the filter 1. Further, the position and width of the molten pool can be measured from an image captured by the filter 2.

[0006]

The groove and the like have a lower light intensity than the arc and are darker, but these portions are also illuminated by the arc light and are recognized by the reflected light. Therefore, as described in Japanese Patent Publication No. 3-71220, when a long wavelength band in which the intensity of the arc light is not so much larger than the intensity of the light from the molten pool is selected by a filter or an infrared television camera and photographed, the arc light is reflected. The brightness of the beveled portion also decreases. Also, as disclosed in Japanese Patent Application Laid-Open No. 54-99754, a method of alternately photographing through a filter 1 that transmits light of a short wavelength side or a filter 2 that transmits light of a long wavelength side is used. Observation and measurement of the position and width of the top end is possible, but when applied to the normally applied V-groove or groove-shaped groove, the intense arc light is naturally the same as the image passed through the filter 1. Since it enters the field of view, an afterimage occurs or a smear phenomenon occurs in the CCD camera, so that the gap at the bottom of the groove or the bead width cannot be photographed well.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an arc welding photographing method and apparatus capable of removing a white noise of an image called a smear phenomenon generated when photographing an arc welded portion by using a CCD camera and obtaining a good welding image. Is the subject.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention uses two CCD cameras and a vertical image taken by one CCD camera and a horizontal image taken by the other CCD camera. By capturing images so as to match each other, a smear phenomenon portion generated in an image of one CCD camera is replaced with a normal image of the other CCD camera, and a good image is obtained.

That is, according to the method for photographing arc welding of the present invention, in the method for photographing the arc generated between the welding wire and the workpiece and the periphery thereof with a CCD camera, the optical axis from the subject to the CCD camera is changed to the optical axis. When the arc welding image is photographed using two CCD cameras after separation by the separator, the vertical image photographed by one CCD camera coincides with the horizontal image photographed by the other CCD camera. And image data obtained by A / D conversion of image signals indicating the respective luminances of the two CCD cameras are stored, and the stored image data indicating the respective luminances coincide with the vertical and horizontal directions of the subject. The image data indicating the luminance is used to combine the images, or the image data indicating one of the luminances is Wherein the combining images employ other image data is greater than the threshold.

In the arc welding photographing apparatus of the present invention,
In an apparatus for photographing an arc generated between a welding wire and an object to be welded and a periphery thereof with a CCD camera, an optical axis from a subject to the CCD camera is separated by an optical axis separator (2) and the optical axis separator (2). The two CCD cameras (3), (4), and two CCD cameras (3), (4), which are separated into two and attached at positions rotated by 90 ° relative to their respective optical axes, A / D converters (5) and (6) for digitally converting image signals, memories (7) and (8) for storing digitally converted image data, memory (7),
Two CCD cameras recorded in (8) (3), (4)
An image data synthesizer (9) for synthesizing image data according to (1) is provided.

Here, the luminance is defined as the energy of light per unit area projected on the image pickup device of the CCD camera.
The image signal defines a voltage corresponding to the luminance as an analog signal output from the CCD camera.
It is defined as a value converted into a digital value by the / D converter. Accordingly, a white portion in the subject has high luminance, and a black portion has low luminance. The image signal output from the CCD camera has a high output voltage in a high luminance portion, and has a low output voltage in a low luminance portion. The image data of the high luminance part is large, and the image data of the low luminance part is small.

[0012]

Hereinafter, the present invention will be described in detail.

As shown in FIG. 1, when photographing the arc welded portion 1, the optical axis 15 is separated into two optical axes A (16) and B (17), and the optical axis 15 is separated by the CCD camera A (3). The optical axis A (16) is photographed as it is, and the CCD camera B (4)
If the image is taken by rotating the optical axis B (17) by 90 degrees at the center, the monitor TV A (13) and the monitor TV B (1)
4), the screen A of FIG. 3 and the screen B of FIG. 4 can be observed, respectively. Since the CCD camera B (4) is rotated at an angle of 90 degrees with respect to the optical axis for photographing, the welding image is displayed at -90 with respect to the screen A
Screen B rotated by degrees is obtained (clockwise is defined as positive). However, the smear phenomenon 50 occurs in the vertical synchronization direction of the image sensor (vertical direction of the monitor television). Here, if the image B is rotated by 90 degrees and overlapped so that the welding image of the image B matches the image A, the white band-like noise portion 50 due to the smear phenomenon has a positional relationship perpendicular to the arc light. . Therefore, by replacing the portion of the screen A where the smear phenomenon occurs and cannot be used as image data with the image data of the screen B, a good image C without the smear phenomenon (FIG. 5)
Can be obtained. In the image A (FIG. 3) in which the smear phenomenon has occurred, the image signal indicating the luminance between h1 and h2 has a white band-like noise portion due to the smear phenomenon in the center S7 to S8 as shown in FIG. The luminance is high and the voltage of the image signal shows the maximum value. Surrounding S1 to S2 and S
Since 13 to S14 are not illuminated by the arc light on the steel sheet surface, they are dark, have low luminance, and have low voltage. S3 ~ S4 and S1
1 to S12 are slightly bright, slightly higher in luminance, and slightly higher in voltage in the groove, as reflected light of arc light. S5 to S6 and S9 to S
Reference numeral 10 indicates that the arc light is slightly reflected on the bead surface, is slightly dark, the luminance is slightly low, and the voltage is slightly low. Therefore, if an appropriate threshold value K is provided, an image signal smaller than K can be determined as a normal portion, and an image signal larger than K can be determined as an abnormal portion of the smear phenomenon. Alternatively, by reading out image data indicating the respective luminances so that the welding images of the image A and the image B coincide with each other, and comparing the two, and using the image data having the smaller value, an image free of smear phenomenon can be obtained. Can be In addition,
The smear phenomenon is a phenomenon peculiar to a CCD camera, and occurs when a high-brightness subject such as arc light is photographed, and a white band-like noise is generated above and below the high-brightness subject. When a high-brightness image is projected on an image sensor, an excessive charge is generated during photoelectric conversion. In the CCD camera, when taking out the electric charge which has been photoelectrically converted and charged as a video signal, the operation of transferring the charged electric charge of the imaging device in the vertical direction and further in the horizontal direction is sequentially and repeatedly taken out. At this time, an excess charge is added to a normal image in the process of transferring in the vertical direction, so that white band noise is generated.

In an image signal output from a general television camera, first, a horizontal one-line signal obtained by scanning from the upper left to the upper right of the screen appears, followed by the second, third, fourth,. The signals of one horizontal line appear sequentially, and the position of one horizontal line is sequentially scanned from top to bottom. In the image A of FIG. 3 taken by the CCD camera A, first, a signal of one horizontal line obtained by scanning from the upper left to the upper right of the welding torch appears, followed by the second, third, fourth,. The signals of each horizontal one line appear sequentially, and the position of one horizontal line is sequentially scanned from above the welding torch to below the groove. CCD camera B
In the image B of FIG. 4 photographed in the above, a signal of one horizontal line obtained by scanning from the upper right side of the welding torch to the lower right side of the groove appears, followed by the second, third, fourth, and fourth signals.・
The signals of one horizontal line appear sequentially, and the position of one horizontal line is sequentially scanned from the right side to the left side of the welding torch. Therefore, the image signals output in order of the image A and the image B do not correspond to the positions of the welding images as they are. Therefore, the welding image of the image B and the image A are matched as follows. That is, CCD camera A and CCD
The image signal of the camera B is A / D-converted, each image data is once digitally stored in a memory, and then the image data is read out from the upper left to the upper right in the image A in the order from top to bottom. In B, the positions of the welding images of the image A and the image B are matched by a method of reading the welding images from the lower left to the upper left in order from left to right.

The optical axis separator 2 in FIG. 1 can use a half mirror or a prism. In this case, the reflected light from the half mirror or the prism is inverted left and right with respect to the transmitted light. This can be corrected as follows. That is, one of the reflected light and the transmitted light is reflected once again using a mirror, and is corrected. Alternatively, the read order of the image data indicating the stored luminance is, for example, reading the image A from the upper left to the upper right in the order from top to bottom in the image A, and reading the image data from the upper left to the lower left in the image B in the order from left to right. Can be reversed left and right.

[0016]

FIG. 1 shows the configuration of an arc welding apparatus used in an embodiment of the present invention, and FIG. 2 shows the configuration of an arc welding apparatus. In the arc welding photographing apparatus shown in FIG. 1, an arc welding portion 1 (arc, molten pool, groove, bead) to be photographed is 90 ° centered on a CCD camera A (3) and an optical axis via an optical axis separator 2. An image was taken with a CCD camera B (4) attached by rotation (clockwise is defined as positive). The optical axis separator 2 was formed using a half mirror and a mirror. First, the optical axis 15
Is incident on the half mirror, and the reflected light is reflected on the optical axis A (16).
Then, the transmitted light was reflected again by using a mirror to obtain an optical axis B (17). Image signals from the CCD cameras A (3) and B (4) were stored in the memories A (7) and B (8) via the A / D converters 5 and 6, respectively.
The memory A (7) and the memory B (8) are each composed of a total of 65536 bytes of n = 256 bytes in the vertical direction and m = 256 bytes in the horizontal direction. CCD camera A, CC
A / D conversion is performed 256 times per one horizontal image signal of the D camera B, and this is repeated 256 times in the vertical direction.
The image data indicating the luminance of the screen is stored in the memory A (7) in M
A (0,0) -MA (m, n) and memory B (8)
MB (0,0) to MB (m, n) (see FIG. 6). Here, MA (i, j) indicates the image data of the address i in the horizontal direction and the address j in the vertical direction of the memory A (7),
MB (i, j) indicates the image data of the address i in the horizontal direction and the address j in the vertical direction of the memory B (8). The image data synthesizer 9 reads out the image data in the memories A (7) and B (8) in the following order, and inverts the image B by 90 degrees so that the image data of the image B matches the image A.
Reading of the image data MA (i, j) from the memory A (7) is performed from the upper left to the upper right (i = 0 to i = m = 2) shown in FIG.
55), from top to bottom (j = 0 to j = n = 2
MA (0,0) to MA (m, 0) MA (0,1) to MA (m, 1) In the order of MA (0, n) to MA (m, n) Read. The image data MB (p, q) in the memory B (8) is from the lower left to the upper left (q = n
= 255 to q = 0) and this is repeated from left to right (from p = 0 to p = m = 255), and MB (0, n) to MB (0,0) MB (1, n ) To MB (1,0)... MB (m, n) to MB (m, 0). However, p = i and q = m-j.

As a method for replacing the image data indicating the luminance of the portion where the smear phenomenon has occurred with the image data indicating a good luminance, the following "method 1 of the present invention" and "method 2 of the present invention" described below were carried out.

In the "method 1 of the present invention", the image data of the portion where the smear phenomenon occurs indicates the maximum value of the image signal.
The value was set to Mm, and the threshold value K for determining the smear phenomenon portion was set to K = 0.95 × Mm. The image data (i, j) in the memory A is compared with K, and MA (i, j) of MA (i, j) ≦ K is set to a normal value.
j) was stored in MC (i, j) of the memory C (10).

When MA (i, j)> K, MA (i, j) is determined to be an abnormal value due to the smear phenomenon,
At this time, the image data MB (p, q) corresponding to the image data MA (i, j) is stored in MC (i,
j).

The “method 2 of the present invention” includes image data MA (i, j) indicating luminance and image data MB indicating luminance.
(P, q) were compared, and the image data with the smaller value was stored in MC (i, j) of the memory C (10).

The image data stored in the memory C (10) was read out, D / A converted by the D / A converter 11, and observed on the monitor television 12.

CCD camera A (3), CCD camera B
(4) and the optical axis separator 2 were mounted on the traveling carriage 18 of the arc welding apparatus shown in FIG. The traveling carriage 18 used had a function of remotely adjusting the position of the welding torch 19 left and right in the groove width direction.

In the welding experiment, the final layer of the multi-layer welding as shown in FIG. 8 was difficult to recognize the groove. Groove depth 1 mm, groove angle 40 degrees, root gap 10 mm
Then, a 1000 mm long test plate extending from the start S through the center M shifted by 10 mm rightward to the end E returning 10 mm leftward was observed while monitoring the monitor television 12, and a carbon dioxide gas shield was remotely operated. Arc welded.
As a comparison, a monitor television A (13) connected to the CCD camera A (3) with an infrared transmission filter that transmits only infrared light having a wavelength of 1.2 to 1.6 μm, which is a conventional method, attached only to the CCD camera A (3). Was welded by remote control while observing.

In the evaluation, the case where there was no welding residue at the groove due to the mistake of the copying operation in the left-right direction was regarded as good, and the case where there was welding residue was regarded as bad.

The results of the welding experiment are shown in Table 1 below. As shown in Table 1, in "Method 1 of the present invention" and "Method 2 of the present invention", the arc and the groove during welding were well observed, so that there was no copying operation error and there was no welding residue on the groove. Therefore, it was determined to be good. With conventional methods, it is difficult to observe the groove,
Immediately after passing through the center M point, a copying operation error occurred, welding residue occurred, and it was determined to be defective.

[0026]

[Table 1]

[0027]

As described above, according to the present invention, it is possible to obtain a good image free from the occurrence of a smear phenomenon when photographing arc welding. For this reason, remote control is facilitated, and automatic control using image data is significantly improved in reliability, thereby contributing to automation and unmanned welding processes.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an arc welding photographing apparatus according to one embodiment.

FIG. 2 is a perspective view showing a main part of an arc welding apparatus according to one embodiment.

FIG. 3 is a front view showing an image A of a monitor television A in which a welding portion is photographed by a CCD camera A;

FIG. 4 is a front view showing an image B of a monitor television B in which a welding portion is photographed by a CCD camera B;

FIG. 5 is a front view showing an image on a monitor television C in which images from the CCD cameras A and B are synthesized by an image data synthesizer.

FIG. 6 is an array diagram schematically showing addresses of image data in a memory A or a memory B;

7 is a waveform diagram of a voltage value of an image signal indicating luminance between h1 and h2 in FIG.

FIG. 8 is a front view of a test plate used in Examples.

[Explanation of symbols]

1: Arc welding part 2: Optical axis separator 3: CCD camera A 4: CCD camera B 5: A / D converter 6: A / D converter 7: Memory A 8: Memory B 9: Image data synthesizer 10 : Memory C 11: D / A converter 12: Monitor TV C 13: Monitor TV A 14: Monitor TV B 15: Optical axis 16: Optical axis A 17: Optical axis B 18: Traveling trolley 19: Welding torch 46: Open Point 47: Molten pool 48: Bead 49: Arc 50: White band noise of smear phenomenon

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B23K 9/095, 9/127 G06F 15/62

Claims (2)

(57) [Claims] An arc welding method for photographing an arc generated between a welding wire and an object to be welded and its periphery by a CCD camera, after separating an optical axis from a subject to the CCD camera by an optical axis separator. When photographing an arc welding image using two CCD cameras, photographing is performed so that a vertical image photographed by one CCD camera coincides with a horizontal image photographed by the other CCD camera. A / D converts the image signal indicating the luminance of each CCD camera
In addition to storing the converted image data, the stored image data indicating the luminance is extracted and compared so that the vertical direction and the horizontal direction of the subject match, and the image data indicating the smaller luminance is adopted. An image combining method, or when image data indicating one of the luminances is greater than a threshold value, employs the other image data to synthesize an image. 2. An arc welding photographing apparatus for photographing an arc generated between a welding wire and an object to be welded and a periphery thereof with a CCD camera, an optical axis separator for separating an optical axis from a subject to the CCD camera. , The optical axis separator (2)
The two CCD cameras (3, 4) and the image signals of the two CCD cameras (3, 4) attached at positions rotated by 90 degrees around their respective optical axes are separated by A / D converters (5, 6) for digital conversion, memories (7, 8) for storing digitally converted image data, and two CCD cameras (3, 4) recorded in memories (7, 8) An imaging device for arc welding, comprising an image data synthesizer (9) for synthesizing image data.