JPH10277743A - Groove tracking control method for electrogas arc welding - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To realize stable groove position detection and welding wire position detection. Provides a groove tracking control method with high reliability and stability. SOLUTION: The average luminance value of the wire image 7m and the sliding plate image 2m is D1, the average luminance value of the groove image 3m is D2, the upper and lower plate surface images (horizontal welding) or the left and right plate surface images (standing). Direction welding)
When the average value of the luminance of the sliding plate image 2m and D1 is D1, Dmin
<D1 <D2 <Dmax, the teaching pattern K1, the surface of the lower plate (left plate), the sliding plate and the teaching pattern K2 of the groove and the upper plate (right plate) satisfying D1 <D2 <Dmax. ) The teaching pattern K3 of the surface, the sliding plate and the groove is previously written in the comparative image memory 13r before the scanning control, and the groove 3, the wire 7 and the sliding plate 2 during welding are stored in the camera 20. The groove position, wire position, and groove width are calculated by calculating the correlation values with the teaching patterns K1, K2, and K3.

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 which takes an image of the vicinity of electrogas arc welding with a television camera, recognizes the relative position between the groove and the torch based on the image signal of the television camera, and opens the automatic welding machine. The present invention relates to an apparatus and a method for performing follow-up control.

[0002]

2. Description of the Related Art Electrogas arc welding in a horizontal position is shown in FIG. 2, and electrogas arc welding in a vertical position is shown in FIG. In both drawings, the z direction is the vertical direction (height direction)
It is. As shown in FIGS. 2 and 3, a tip 1 of a welding torch mounted on a traveling trolley (not shown) is inserted into a groove 3 and oscillated in a thickness direction x, and cooled so as to cover a welding arc. The sliding plate 2 is brought into contact with the groove 3, and is slid according to the welding rod (y direction or z direction). The cooling sliding plate 2 has a shield gas outlet (not shown), which covers the welding arc and the molten metal surrounded by the groove and the cooling sliding plate 2 with the shielding gas and prevents dripping of the molten metal. There is a function to assist bead formation. The bogie traveling speed is controlled to be high when the welding current value exceeds a predetermined value, and to be low when the welding current value is less than the predetermined welding current value, so that the protrusion length of the welding wire 7 is kept substantially constant. Be lucky.

In the groove tracking control of the electrogas arc welding, the distance between the lower edge 9 and the wire 7 needs to be kept constant in the horizontal position (FIG. 2), and the left edge and the right edge in the vertical position (FIG. 3). It is necessary to keep the wire 7 in the center. For the scanning control, the welding torch is supported by an electric scanning shaft on a bogie, and the welding torch and the cooling sliding plate are electrically driven in the groove width direction (z direction in FIG. 2 and y direction in FIG. 3). There is a copying mechanism. When performing the scanning control, the electric scanning shaft is moved by a predetermined distance by an electric scanning shaft driven by an electric motor. However, the sliding load of the cooling sliding plate 2 causes the electric scanning shaft to bend, thereby cooling the welding torch (chip 1) and the cooling. The sliding plate 2 does not necessarily move by the scanning shaft drive amount. In other words, the movement amount of the welding torch and the cooling slide plate varies with respect to the scanning shaft drive amount.

In general, in the groove tracking control, a contact type sensor such as a roller type is mounted in front of a welding arc to detect a groove position, and corrects a welding torch position according to the detected groove position. In this case, since the welding torch position is not detected, it is necessary that the relative positional relationship between the sensor and the welding torch at the start of the copying control be maintained at any point during the copying control. However, in the electrogas arc welding, the relative positional relationship between the sensor and the welding torch cannot be kept constant due to the deflection of the scanning shaft and the like due to the sliding load of the cooling sliding plate 2 and its fluctuation. Therefore, good copying control could not be performed by detecting the position of only the groove.

As a method for solving this problem, Japanese Patent Laid-Open No.
In Japanese Patent Application Laid-Open No. 9-94583, a welding wire and a groove during arc welding of narrow groove welding are photographed by a television camera, image data on a photographed screen is processed, and the position of the welding wire with respect to the groove is determined. A groove tracing control method for adjusting the position of the welding torch so as to correct the displacement of the welding wire with respect to the groove has been proposed. Both sides of the screen (corresponding to the surface of the steel plate) are shaded by arcs and molten pool radiation, and the groove is brightly photographed, and the welding wire is photographed almost in the center of the groove. Have been.

Therefore, it is described that the groove position, the width, and the wire position can be measured by determining an appropriate threshold value for the luminance data in the groove width direction of the photographed image data and determining it. Such a method of providing an appropriate luminance threshold value and making a determination is called a binarization method.

As described above, in the method of controlling the groove tracing using the image data obtained by photographing the welding wire and the groove with the television camera, the groove and the wire position can be detected at the same time. Scanning control can be performed so as to keep the relative distance constant, and good scanning control should be possible even if the scanning shaft or the like is bent.

A case where this method is applied to a horizontal posture of electrogas arc welding will be described. FIG. 1 shows a photographing screen obtained by photographing the vicinity of the tip 1, the cooling slide plate 2, and the groove 3 at the tip of the welding torch to be subjected to electrogas arc welding from above the groove with the TV camera 20 as shown in FIG. .
FIG. 5 shows the luminance distribution on the scanning line L1 in FIG.

FIG. 1 and FIG. 5 show that a-
Between point b and point ef, shadow is formed on the surface of the steel sheet and the brightness is low. Between point bc and point de, the inside or groove of the groove illuminated by arc light or molten pool radiation light. The brightness is high on the hypotenuse, and between the points cd, the inside of the groove or the hypotenuse of the groove having high background luminance is shaded by the wire, and the brightness is low.

FIG. 6 shows a luminance distribution on the scanning line L1 in a dark image of only the radiation light of the molten pool due to the short-circuit during the transfer of the droplet and the arc disappearing. FIG. 7 shows a luminance distribution on the scanning line L1 of an image when the arc length is long, the arc flame is large, the wire is wrapped around, and the whole wire is bright, and the shade of the wire is thin.

In FIG. 5, the brightness threshold value B1 is set and the image data is binarized (by cutting out the high brightness portions SU and SD on the groove on both sides of the wire) to generate SU, S
The groove position and width are determined from the position D and the width in the Z direction, and S
By determining the relative position in the Z direction of the low luminance portion (corresponding to the wire) between U and SD with respect to SU and SD, the position of the wire with respect to the groove (Z direction) is determined. However, the arc disappears and in FIG. 6, SU and SD cannot be cut out unless the threshold value is reduced from B1 to B2. In FIG. 7 where the arc length is long, unless the threshold value is increased from B1 to B3,
A low-luminance portion corresponding to a wire cannot be cut out from a high-luminance portion (SU to SD). That is, the wire position cannot be measured.

As described above, in the binarization method, it is necessary to set an appropriate threshold value in accordance with a change in the brightness of a captured image. In the welding arc phenomenon, the brightness changes frequently and greatly,
Determination of the threshold is a major issue, and stable measurement has been difficult.

[0013]

As described above, in electrogas arc welding, bending of a scanning shaft or the like due to a sliding load of a cooling sliding plate is unavoidable. Can not. In the method of detecting a groove and a welding wire by binarization using image data obtained by photographing the welding wire and the groove during arc welding with a television camera, the brightness of the arc light fluctuates drastically. Setting thresholds is difficult.

The present invention realizes stable groove position detection and welding wire position detection even under such conditions.
An object of the present invention is to provide a groove copying control method with high reliability and stability.

[0015]

[Means for Solving the Problems]

(1) A method for controlling the groove tracing of electrogas arc welding in a horizontal position using image data of a groove (3), a welding wire (7) and a cooling sliding plate (2) taken simultaneously by a television camera (20). In the photographing screen of the TV camera (20), the average value of the brightness of the welding wire (7m) and the cooling slide plate (2m) is D1, the average value of the brightness in the groove (3m) is D2, and Assuming that the average value of the luminance of the plate surface and the cooling slide plate (2m) is D1, Dmin <D1 <D2 <Dmax (1) where Dmax is the maximum value that can be taken as image data corresponding to the luminance. The welding wire in the comparative image memory (13r) must satisfy the minimum value that can be taken as image data corresponding to the brightness.
(7m) in a region corresponding to the first region (P1) including the welding wire and the image data of the groove as the teaching pattern K1, the second region (P2) including the lower edge of the groove and the cooling sliding plate. ) On the lower plate surface,
Teaching pattern K2 for cooling slide plate and groove image data
Is written in advance before the copying control; an area I1 (P1) having a high correlation with the teaching pattern K1 is searched from the image data taken by the television camera (20) during the copying control to determine the welding wire position. Then, an area I2 (P2) having a high correlation with the teaching pattern K2 is searched to determine the groove lower edge position, and the welding torch (1) is determined according to the determined wire position and lower edge position.
And controlling the vertical position of the cooling sliding plate (2).

To facilitate understanding, reference numerals in parentheses for corresponding elements or items in the embodiment shown in the drawings and described later are added for reference.

It is desirable that the groove, wire and tip positions in the groove profiling control be detected at a position as close as possible to the welding arc from the viewpoint of profiling accuracy. However, the welding arc is hidden by the cooling sliding plate, and the closest position to the welding arc that can be detected is the intersection between the cooling sliding plate and the groove, and the intersection between the cooling sliding plate and the wire. Wire image (7m) and cooling slide plate image (2
There is a remarkable difference between (m) and the position (distribution) and brightness on the screen, and relative identification by image processing is easy.

In the present invention, since the image (2m) of the cooling sliding plate is used for specifying (recognizing) the image area including the wire image (7m), the recognition accuracy of the image area is high, and Accurate detection of the wire position (z / y) at the intersection of the wires is realized.

The images captured during the groove profiling control include variations in arc light, scattering of spatter and fumes, changes in groove edges,
There is fluctuation such as bending of the wire. Teaching patterns K1, K
2 is preferably an average image photographed during the groove copying control. However, the image taken while welding before the copying control has the same fluctuation as during the groove copying control,
It takes time to obtain a stable teaching pattern.

Area I that matches teaching patterns K1 and K2
In one method of determining 1 (P1) and I2 (P2), as will be described later, the correlation coefficient between the captured image data and the teaching pattern is determined.
It is calculated using equation (2). In this case, the teaching pattern is
It is not necessary that the image be taken while welding.
Therefore, a teaching pattern is set as follows.

A method of writing a numerical value corresponding to the luminance into the memory: The teaching pattern stores the numerical values (image data) corresponding to the luminances D1 and D2 in the comparative image memory (13r) on the welding wire, the lower plate surface, and the cooling slide. Write to the memory address corresponding to the board and groove.

A method for photographing a pseudo groove: A pseudo groove (FIG. 21) which can obtain image data substantially equal to image data photographed while welding is photographed by a television camera and written into a comparative image memory (13r). . When the pseudo groove was photographed with a television camera (20), the brightness D1 of the welding wire, the cooling sliding plate and the lower plate surface was low (dark), and the brightness D in the groove was low.
2 is drawn on a plane so as to be higher (brighter) than D1 and to satisfy the expression (1). In addition, the pseudo groove is drawn and photographed so that the positions of the welding wire, the cooling sliding plate and the lower plate edge are substantially the same as the images photographed while welding.

Since the image data of the teaching patterns K1 and K2 represented by the data of the comparison image memory in which the image data is written as described above or above is substantially equal to the image data of the image photographed while welding, the teaching pattern The positions of the welding wire, the cooling sliding plate, and the lower plate edge detected in the comparison with the patterns K1 and K2 are obtained by translating the corresponding positions in the comparative image memory in the y and z directions. Further, since there is little variation in the teaching pattern, a stable detection result can be obtained.

(2) A pseudo groove drawn so as to satisfy the above equation (1) is photographed in advance before the copying control, and from the obtained image data, the image data of the region including the welding wire is used as the teaching pattern K1. Then, the image data of the area including the lower edge and the cooling sliding plate is written into the comparative image memory as the teaching pattern K2. This is the aspect described above.

(3) A method for controlling the groove tracing of the electrogas arc welding in the horizontal posture using image data obtained by simultaneously photographing a groove, a welding wire and a cooling sliding plate with a television camera. The average value of the brightness of the welding wire and the cooling sliding plate is D1, the average value of the brightness in the groove is D2, the average value of the brightness of the lower plate surface and the cooling sliding plate is D1, and the upper plate surface is cooling. Assuming that the average value of the luminance of the sliding plate is D1, Dmin <D1 <D2 <Dmax (1) where Dmax is the maximum value that can be taken as image data corresponding to luminance Dmin: is image data corresponding to luminance In order to satisfy the minimum possible value, the welding wire and the image data of the groove are used as the teaching pattern K1 in the area corresponding to the first area including the welding wire on the comparative image memory, and the lower edge of the groove is used. And cooling sliding plate The image data of the lower plate surface, the cooling slide plate and the groove in the second area is used as a teaching pattern K2, and the upper plate surface and the cooling slide are formed in the third region including the groove upper edge and the cooling slide plate. The moving plate and groove image data are written in advance as a teaching pattern K3 before the copying control; an area having a high correlation with the teaching pattern K1 from the image data taken by the television camera during the copying control. I1 is searched to determine the position of the welding wire, the area I2 having a high correlation with the teaching pattern K2 is searched to determine the lower edge position of the groove, and the area I3 having a high correlation with the teaching pattern K3 is searched and the area above the groove is searched. Determining the edge position, controlling the vertical position of the welding torch and the cooling sliding plate according to the determined wire position and the lower edge position, and switching the welding conditions according to the determined lower edge position and the upper edge position; Features.

This is the same as the above embodiment (1) except that the teaching pattern K is composed of the upper plate surface, the cooling slide plate and the groove image data.
In addition, the upper edge position of the groove is obtained with reference to the teaching pattern K3, and the welding conditions are also switched according to the lower edge position and the upper edge position. The position difference between the lower edge position and the upper edge position corresponds to the groove width, and the welding condition is switched to correspond to the groove width. According to this, the vertical positioning control of the welding wire and the cooling sliding plate with respect to the groove and the automatic control of the welding condition with respect to the groove width are simultaneously performed, and accurate welding is performed on the groove.

(4) In the above (3), a pseudo groove drawn so as to satisfy the expression (1) is photographed in advance before the copying control,
From the obtained image data, the image data of the area including the welding wire is used as the teaching pattern K1, and the image data of the area including the lower edge and the cooling slide plate is used as the teaching pattern K2.
The image data of the area including the upper edge and the cooling sliding plate is written in the comparative image memory as the teaching pattern K3.
This is a modification of the above (3).

(5) A method for controlling a groove in electrogas arc welding in a vertical position using image data of a groove, a welding wire and a cooling sliding plate simultaneously photographed by a television camera. Above, the average value of the brightness of the welding wire and the cooling slide plate is D1, the average value of the brightness in the groove is D2, the average value of the brightness of the left plate surface and the cooling slide plate is D1, and the right plate surface is D1. Assuming that the average value of the brightness of the cooling sliding plate is D1, Dmin <D1 <D2 <Dmax (1) where Dmax is a maximum value that can be taken as image data corresponding to the brightness Dmin: image data corresponding to the brightness The image data of the welding wire and the groove as the teaching pattern K1 in the area corresponding to the first area including the welding wire on the comparative image memory so as to satisfy the minimum value Including edge and cooling sliding plate The image data of the left plate surface, the cooling slide plate and the groove in the second area are used as the teaching pattern K2, and the right plate surface and the cooling slide are formed in the third region including the right edge of the groove and the cooling slide plate. The moving plate and groove image data are written in advance as a teaching pattern K3 before the copying control; an area having a high correlation with the teaching pattern K1 from the image data taken by the television camera during the copying control. The position of the welding wire is determined by searching I1, the region I2 having a high correlation with the teaching pattern K2 is searched to determine the left edge position of the groove, and the region I3 having a high correlation with the teaching pattern K3 is searched and the groove right is searched. The edge position is determined, and the left and right positions of the welding torch and the cooling sliding plate are controlled in accordance with the determined wire position, left edge position and right edge position. This is an aspect obtained by converting the aspect of the horizontal orientation described in (3) above into an aspect suitable for a vertical orientation.

(6) In the above (5), a pseudo groove drawn so as to satisfy the above equation (1) is photographed in advance before the copying control,
From the obtained image data, the image data of the region including the welding wire is used as the teaching pattern K1, and the image data of the region including the left edge and the cooling slide plate is used as the teaching pattern K2.
The image data of the area including the right edge and the cooling sliding plate is written in the comparative image memory as the teaching pattern K3.
This is a modification of the above (5).

In the above (1) to (6), the area I1 detected by the correlation search on the photographing screen of the television camera (20) during the copying control welding is written in the comparative image memory (13r) in advance. As in the case of the teaching pattern K1 (P1), which includes a welding wire, the wire image (7 m) in the region I1 is included.
Is substantially the same as the position of the wire image (7m) in the teaching pattern K1 (P1). Similarly, the region I2 detected by the correlation search is, like the teaching pattern K2 (P2) previously written in the comparative image memory (13r), a groove-equivalent image on the photographing screen and a steel plate connected to the groove. It includes a surface equivalent image, and the position of the groove lower edge or the left edge in the region I2 is substantially the same as the position of the groove image in the teaching pattern K2 (P2). The positional relationship between the teaching pattern K2 (P2) and the region I2 can be understood from the positions of both regions on the photographing screen.
Since the positional relationship between the teaching pattern K1 (P1) and the teaching pattern K2 (P2) is predetermined, the relative positional relationship between the region I1 / I2 and the relative positional relationship between the teaching pattern K1 (P1) / K2 (P2). , The position of the wire appearing in the region I1 with respect to the groove edge appearing in the region I2 can be calculated.

For example, when the image corresponding to the area P1 shown in FIG. 1 is defined as the teaching pattern K1 and the image corresponding to the area P2 is defined as the teaching pattern K2 in the comparative image memory 13r based on the positional relationship between the areas shown in FIG. The distance between the centers of the patterns K1 and K2 in the groove width direction Z (z in FIG. 2 corresponds to y in FIG. 3) is Zt, and the distance between the areas I1 and I2 on the photographing screen during welding is Zt. Assuming that the area center line distance is Zr, the area center line distance Zr on the captured image is Zr-Zt more than the area center distance Zt, and the welding wire 7 is shifted in the groove width direction Z with respect to the groove 3. That is, based on this relationship, the difference (wire position difference) between the current relative position (Zt) and the relative position (Zt) between the groove 3m and the welding wire 7m on the image on the comparative image memory 13r. Is found. Hereinafter, this will be described in more detail.

In general, an image signal output from a television camera is an analog voltage corresponding to luminance. The image signal output order is such that the luminance signal in the horizontal direction Z from the upper end to the lower end in FIG. It is output sequentially in all vertical directions Y. Therefore, in order to handle as image data, the number of pixels in the horizontal direction Z (s pixels) and the number of pixels in the vertical direction Y (t pixels) are determined in advance, and the number of memories (s × t pixels) according to the total number of pixels is determined. ) Is prepared, and the analog voltage (image signal) of the luminance signal output in the above order is digitalized while taking timing so that the luminance at an arbitrary position on the screen is associated with the data at a predetermined address in the memory. The data is converted into data (image data) and the data is stored at a predetermined address in the memory. That is, the teaching patterns K1 (P1), K
2 (P2) and K3 (P3) are written separately for each pattern. Alternatively, the teaching patterns K1 (P1), K2 (P
2) The image data of the entire screen (s × t pixels) including K3 (P3) is stored in the comparison image memory 13r,
Area information to be cut out as the teaching patterns K1 to K3 (the address of the diagonal corner of the area) is stored in the memory as control information.

The screen (s × t) photographed during the copying control has an image similar to that of FIG. 1 although there are fluctuations in the groove, the position of the wire and the arc, and fluctuations in brightness.
First, an upper left corner Z = 1, Y = 1, that is, (1, 1) is an upper left corner, and (m, n) is a lower right corner (the same size as the teaching pattern K1) on this photographing screen. Area) is defined as an input pattern (m.times.n) I1, and the upper left corner of each of the teaching pattern K1 and the input pattern I1 is defined as (1, 1) in the horizontal direction. Numbers are assigned in the vertical direction up to the m-th position up to the n-th position.
The luminance represented by one image data is represented by W (i, j), respectively.
And U (i, j), the correlation coefficient R11 between the luminance W of the teaching pattern K1 and the luminance U of the input pattern I1 is calculated by the following equation (2).

[0034]

(Equation 2)

The correlation coefficient R11 between the teaching pattern K1 and the input pattern I1 is obtained. Next, the pixel (2, one pixel below the upper left corner (1, 1) taken during the scanning control
1) Correlation coefficient R of input pattern I1 with upper left corner
21 is similarly calculated by equation (2). Thus, the correlation coefficient R
When the calculation for obtaining IJ is executed for one line from the upper left corner (1, 1) to (sm, 1) of one screen during the copying control, the calculation is similarly performed by shifting the line (pixel in the Z direction) rightward. (In the direction in which Y increases), and the processing is performed up to the line t−n. When this is completed, if the position (I = Zc, J = Yc) where the correlation coefficient RIJ is the largest is found, (Zc, Yc)
c) is the upper left corner, and (Zc + m-1, Yc + n-1)
Is a lower right corner, a region of m × n pixels is a region I1 (extraction pattern) including a wire image, which is equivalent or similar to the teaching pattern K1.

At this time, as shown in FIG. 8, the horizontal axis represents the luminance of the teaching pattern K1 (P1), and the vertical axis represents the luminance of the extracted pattern corresponding to the above. If the brightness of each pixel of m-n × n is plotted in association with each other, if the teaching pattern K1 and the input pattern I1 have substantially the same brightness, they are distributed around a line of about 45 ° (Q1). However, when the extracted pattern I1 is darker, it is distributed below the 45-degree line as shown as Q2, and when the extracted pattern is brighter, it is above the 45-degree line as shown as Q3. Distributed.

What is important here is that Q1, Q2,
The spread of the luminance plot distributed in Q3 corresponds to the correlation coefficient R, but the spread of the plots of Q1, Q2, and Q3 has a small difference. That is, the correlation coefficient R is less affected by fluctuations in brightness.

Each of the regions P1 to P5 shown in FIG.
It is enlarged and shown in FIGS. If the areas P1 to P5 are used as teaching patterns, the position of each image in each area can be similarly detected by the above method.

Therefore, as a method of obtaining the position of the wire in the groove, in the horizontal orientation (FIG. 2), the region P1 or P5 including the wire image 7m or the region P1 including the chip image 1m.
4 is similarly detected by the above method, and the region P2 including the groove lower edge image 9m is similarly detected by the above method, and the detected region P
The position of the wire or chip with respect to the lower edge of the groove is calculated from the position difference in the Z direction between P1, P5 or P4 and P2.

In the upright posture (FIG. 3), not only the area P2 including the left edge of the groove but also the area P3 including the right edge is similarly detected by the above-described method, and the Z-direction positions of these areas P2 and P1 are detected. Is calculated, and the midpoint of those positions is calculated as the groove center, and the position of the wire or chip with respect to this midpoint is calculated.

As a method of obtaining the groove width, in the horizontal posture (FIG. 2), the lower edge region P2 and the wire regions P1, P5 or P4 are extracted and the wire position with respect to the lower edge is calculated. In the vertical posture (FIG. 3), the left edge region P2 and the right edge region P3 and the wire regions P1, P5 or P4
Is calculated, and the wire position with respect to the groove center is calculated.

The reason why the image extraction area is set to P2, P1, P3, P4, and P5 shown in FIGS. 1 and 9 to 13 will be described. It is desirable that the groove, wire and tip positions in the groove profiling control can be detected at a position as close as possible to the welding arc from the viewpoint of profiling accuracy. However, the welding arc is hidden by the cooling sliding plate 2, and the closest position to the welding arc that can be detected is the intersection between the cooling sliding plate 2 and the groove 3 and the intersection between the cooling sliding plate 2 and the wire 7.

If the extracted regions of the lower edge and the upper edge are regions that do not include the image 2m of the cooling sliding plate 2 as indicated by P2 and P3 shown in FIG. 14, the region P2 is an area shown in FIG. In the meantime, P3 detects an arbitrary position Z between the way and the way. Since the photographing is not always perpendicular to the groove, when the tip image 1m and the wire image 7m are inclined with respect to the Y axis of the screen as shown in FIG. When the upper edge is at a position close to c, a large error occurs when obtaining the groove width. In some cases, P2 in FIG. 14 detects the top edge of the chip and P3 detects the bottom edge of the chip, and stable detection is not possible. Therefore, the lower edge and upper edge extraction areas P2 and P3 (teaching pattern K
2, K3) is preferably an area including the image 2m of the cooling sliding plate 2 as shown in FIGS.

If the teaching pattern of the chip is P4 as shown in FIG. 14, the insertion angle of the chip is not always parallel to the groove. If detected, the distance between the lower edge and the chip fluctuates, and stable detection cannot be performed. Therefore, it is desirable that the extraction area P4 (teaching pattern) of the chip includes the chip and the wire, as shown in FIG.

Assuming that the wire teaching pattern is P
Even when the image 2m of the cooling sliding plate 2 is not included as shown in FIG.
Since the length at which the wire 2 is photographed is short, the fluctuation of the detection position is small. Therefore, FIG. 13 including the image 7m of the wire 7 or the image 7m of the wire 7 and the image 2m of the cooling sliding plate 2
In FIG. 10 including the above, stable detection can be performed.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0047]

FIG. 15 shows the configuration of an automatic welding apparatus used in an embodiment of the present invention, and FIG. 16 shows the configuration of a control apparatus. Oscillating shaft motor 34 of welding torch, cooling slide plate 2, TV camera 20
The electric tracing shaft 33 to which is mounted is a traveling carriage 3 that travels on a rail 31 juxtaposed to the groove 3 via a rotating shaft 35.
2 attached. The cooling sliding plate 2 is pressed against the groove 3 with a constant load to form a bead during welding.
By modifying the scanning shaft 33, the welding torch and the cooling sliding plate 2, T
The V camera 20 moves integrally in the groove width direction. The TV camera 20 was installed at the position shown in FIG. 4 and photographed the range shown in FIG. A microcomputer 10 including a CPU and a memory detects a signal of a limit switch 15 for detecting a position just before the swinging of the welding torch.
An analog image signal from the TV camera 20 is converted into a digital signal by the A / D converter 14 at substantially the intermediate point in the period in which the image 5 is closed, and the image data for one screen is 480 pixels vertically and horizontally. Image data of 512 pixels is stored in the image memory 1
3 is stored. The limit switch 15 is closed once in each stroke of the reciprocating motion of the swing shaft 34.

The microcomputer 10 has the image memory 1
From the image data (1 screen) of the third comparative image memory 13r
Teaching pattern K1 (P1, P4 or P
5), regions I1 (P1, P4 or P5) and I2 (P2) having higher correlation function values with respect to K2 (P2) and K3 (P3).
2) and I3 (P3) are extracted, the Z position of the wire with respect to the groove is calculated from the extracted relative position between the regions, and a signal corresponding thereto is commanded to the servo amplifier 11 so that the scanning shaft 3
3 was controlled. In addition, TV camera 2
The analog image signal from 0 is supplied to the VTR via the distributor 23.
An image of the groove 3, the wire 7, the chip 1, the cooling slide plate 2 and the like during the scanning control was stored.

The photographing range was adjusted so that the distance on the steel plate surface was 0.06 mm per pixel.

As a method of confirming the scanning controllability, a scanning control image during welding was recorded by the VTR 21, and after the welding was completed, the image was reproduced on the monitor TV 22 and measured on a scale for conversion.

[Embodiment 1] One embodiment of the present invention which employs a method and apparatus for controlling the groove tracking of electrogas arc welding according to the present invention in transverse electrogas arc welding will be described. As shown in FIG. 18, using the welding test plate with the backing material 4 attached thereto, the groove thickness was 25 mm, the surface gap was 10 to 15 mm, the back gap was 4 to 9 mm, and the length was 50 as shown in FIG.
Using a 0 mm test plate, the welding conditions were a welding current of 350
(A), welding voltage 31 (V), flux-cored wire 1.6 (mmφ), welding speed 10.4 (cm / mi)
n) and the number of swings 42 (times / min) were used.

The TV camera 20 being welded under these conditions
Analysis of the image data taken at
The D1 value of the cooling sliding plate, the upper plate surface, the lower plate surface and the chip was 20 to 60, and the D2 value in the groove was 80 to 140. Note that the A / D conversion of the analog image signal is 8 bits, and the possible range of the image data is 0 to 255.

In response to this, the pseudo groove shown in FIG.
2.5 mm, the welding wire width is 1.6 mm, the distance between the lower edge and the wire is 6 mm, and the sliding copper plate and chip are drawn.
The shading was adjusted so that 1 was 30 to 50 and D2 was 100 to 120, drawing was performed on paper, and photographing conditions were adjusted.

The teaching pattern was obtained by attaching a pseudo groove at the groove position of the welding test plate and photographing with the television camera 20. The photographed image data was written into the comparative image memory 13r, and areas P4, P2 and P3 on the image were designated and registered as teaching patterns K1, K2 and K3, respectively.

1-1 Experimental Method The operator starts welding, drives the traveling carriage 32, starts driving the swing shaft 34, and optimally sets the position of the wire in the Z direction with respect to the lower edge of the groove. The microcomputer 10 was instructed to start the copying control.

The microcomputer 10 writes the image data for one screen shot into the image memory 13 in response to the closing signal of the limit switch 15, and reads the image data from the image memory 13 to the same size as the wire teaching pattern K1 (P4). The input patterns were sequentially extracted at different positions, and the correlation coefficient with the teaching pattern was calculated according to equation (2). When the largest correlation coefficient is 0.6 or more, the position is determined to be the wire position, and the position ZP4 in the groove width direction is stored. Similarly, the lower edge teaching pattern K2 (P
2) and areas (P2, P3) having a high correlation with the upper edge teaching pattern K3 (P3) are extracted and their positions ZP1 are extracted.
And ZP3 are detected, and a wire / lower edge distance Zt =
The microcomputer 10 calculates ZP4-ZP1 and Zw = ZP3-ZP1, and the microcomputer 10 calculates the deviation of the wire / lower edge distance Zt obtained from the image data for one screen with respect to the reference value Zs. , Scanning shaft 33
Was driven in the z direction to correct the welding torch and the cooled sliding copper plate to the reference position Zs with respect to the groove, and the welding conditions were switched according to the conditions in Table 1 according to Zw.

The microcomputer 10 has the above-described configuration.
Is repeated until the distance Zt between the wire and the lower edge becomes the reference value Z.
In the direction s, the servo motor 12 was instructed to drive the torch and the cooling sliding copper plate to correct the z position of the scanning shaft 33, and the welding conditions were corrected according to Zw = ZP3-ZP1 and Table 1. .

[0058]

[Table 1]

1-2 Experimental Results It has been confirmed that the scanning control of the distance between the wire and the lower edge can be favorably controlled within a range of ± 0.3 mm. Further, the welding condition switching control according to the width between the upper edge and the lower edge of the groove is such that the switching can be accurately performed within the range of ± 0.3 mm according to the switching set value shown in Table 1 according to the variation of the surface gap. confirmed. FIG. 23 shows the result of the welding condition switching control state. The condition is switched from condition 1 to condition 2 at a welding distance of 230 mm, and is switched from condition 2 to condition 3 at a welding distance of 400 mm. It was confirmed that it could be performed accurately and accurately.

[Second Embodiment] The welding conditions are the same as in the first embodiment. However, the teaching patterns were set as follows. That is, the image data of the teaching pattern on the comparative image memory obtained in Example 1 is analyzed, and as a result, D1 = 4
0, D2 = 110, the microcomputer 10 is operated by an operator input via the operation board,
In the comparative image memory 13r, D1 is written in the entire region of the welding wire region, the cooling sliding plate region, the upper plate surface region, the lower plate surface region, and the chip region, and D2 is written in the entire groove region. I wrote it.

2-1 Experimental Method The experimental method used in Example 1 was used.

2-2 Experimental Results It has been confirmed that the scanning control of the distance between the wire and the lower edge can be favorably controlled within a range of ± 0.3 mm. Example 1
Similarly to the above, it was confirmed that the welding condition switching control according to the width between the upper edge and the lower edge can be switched accurately within the range of ± 0.3 mm according to the switching set value shown in Table 1 according to the fluctuation of the surface gap. did. FIG. 24 shows the result of the condition switching control state after welding.
Is switched from condition 1 to condition 2 at
The condition was switched from condition 2 to condition 3 at 0 mm, and it was confirmed that the fluctuation of the surface gap and the condition switching could be performed accurately and accurately.

[Embodiment 3] A description will be given of an embodiment using a method and an apparatus for controlling the groove tracking of electrogas arc welding according to the present invention in elevating electrogas arc welding.
The welding test plate used was a V-shaped groove as shown in FIG.
A test plate having a plate thickness of 25 mm, a surface gap of 17 to 25 mm, a back gap of 5 to 10 mm, and a length of 700 mm was used. The welding conditions were welding current 420 (A) and welding voltage 41.
(V), flux-cored wire 1.6 (mmφ), welding speed 11.0 (cm / min), swing width 8 mm, and swing frequency 30 (times / min) were used. In addition, as the copying control condition, as shown in FIG.
By turning the camera 90 degrees to the right, a shooting screen in the same mode as the shooting screen shown in FIG. 1 can be obtained. In this case, the Z direction of the screen is the x direction shown in FIG. 3, and the Y direction of the drawing is the z direction shown in FIG.

The TV camera 20 being welded under these conditions
Analysis of the image data taken at
The D1 value of the cooling sliding plate, the right plate surface, the left plate surface and the chip was 20 to 60, and the D2 value in the groove was 80 to 140. Also in this example, the A / D conversion of the analog image signal of the television camera 20 is 8 bits, and the possible range of the image data is 0 to 255.

In response to this, the pseudo groove shown in FIG.
1.0 mm, the welding wire width is 1.6 mm, the distance between the left and right edges and the wire is 10.5 mm, the lower edge and the distance between the wires are 6 m, and a sliding copper plate and chip are drawn. D1 is 30 to 5
The shading was adjusted so that 0 and D2 were 100 to 120, and drawing was performed on paper, and the photographing conditions were adjusted.

The teaching pattern was obtained by attaching a pseudo groove at the groove position of the welding test plate and photographing with the television camera 20. The photographed image data was written into the comparative image memory 13r, and areas P4, P2 and P3 on the image were designated and registered as teaching patterns K1, K2 and K3, respectively.

3-1 Experimental method The operator starts welding, drives the traveling carriage 32, starts driving the swing shaft 34, and positions the wires in the X and Z directions with respect to the left and right edges of the groove. Was set optimally, and the microcomputer 10 was instructed to start the copying control.

The microcomputer 10 writes the captured image data for one screen into the image memory 13 in response to the closing signal of the limit switch 15, and then reads the wire teaching pattern K1 (from the image memory 13) on the comparative image memory 13r. The position of the input pattern having the same size as that of P2) is changed and sequentially taken out, and the correlation coefficient with the teaching pattern K1 is calculated by (2)
Calculate according to the formula. If the largest correlation coefficient is 0.6 or more, it is determined as a wire position, and the coordinate position ZP2 in the groove width direction is stored. Similarly, of the image in the image memory 13,
A region having a high correlation with the left edge teaching pattern K2 (P1) and the right edge teaching pattern K3 (P3) is extracted, its positions ZP1 and ZP3 are detected, and their positional difference (groove width) Zw = ZP3-ZP1. Is calculated, the position of the intermediate point Zwp = ZP3 + Zw / 2 is calculated, and the position difference (wire / groove center distance) Zt = Zwp-ZP2 of the designated area P2 with respect to Zwp is calculated. The deviation of the wire / groove center distance Zt obtained from the image data of (1) with respect to the reference value Zs is calculated, and the scanning shaft 33 is driven by the deviation corresponding to the deviation to obtain the welding torch and the cooling sliding copper plate. Was corrected to the reference position Zs for the groove, and the welding conditions were switched in accordance with the conditions in Table 2 corresponding to the groove width Zw.

The microcomputer 10 has the above-described configuration.
Is repeated, and the distance Z between the wire and the groove center during the scanning control is changed.
By comparing t = Zwp-ZP2 with the scanning control reference Zs, a command is given to the servomotor 12 in a direction in which the difference becomes smaller, the scanning shaft 33 is corrected, and the table shown in Table 2 corresponding to the groove width Zw. The welding conditions were modified according to the conditions.

[0070]

[Table 2]

3-2 Experimental Results As shown in FIG.
As a result of performing control on the shooting screen shown in FIG.
± 0.3 in the scanning control of wire / groove center distance
It was confirmed that control could be performed well within the range of mm. Further, it was confirmed that the condition was accurately switched from the condition 1 to the condition 2 according to the switching condition shown in Table 2, and that it was possible to accurately switch according to the fluctuation of the surface gap. FIG. 25 shows the result of the condition switching control state after welding. The condition was switched from condition 1 to condition 2 at a welding distance of 220 mm, and it was confirmed that the fluctuation of the surface gap and the condition switching were performed accurately and accurately.

Embodiment 4 The welding conditions are the same as in Embodiment 3 described above. However, the teaching patterns were set as follows. That is, the image data of the teaching pattern on the comparative image memory obtained in the third embodiment is analyzed, and as a result, D1 = 4
0, D2 = 110, the microcomputer 10 is operated by an operator input via the operation board,
In the comparative image memory 13r, D1 is written in the entire region of the welding wire region, the cooling sliding plate region, the left plate surface region, the right plate surface region, and the chip region, and D2 is written in the entire groove region. I wrote it.

4-1 Experimental Method The experimental method used in Example 3 was used.

4-2 Experimental Results In the same manner as in Example 3, it was confirmed that, in the copying control of the distance between the wire and the groove center, it was possible to control well within a range of ± 0.3 mm. Further, it was confirmed that the condition was accurately switched from the condition 1 to the condition 2 according to the switching condition shown in Table 2, and that it was possible to accurately switch according to the fluctuation of the surface gap. FIG. 26 shows the result of the condition switching control state after welding. The condition was switched from condition 1 to condition 2 at a welding distance of 260 mm, and it was confirmed that the fluctuation of the surface gap and the condition switching were performed accurately and accurately.

[0075]

The method of the present invention has basic characteristics that are not easily affected by variations in the brightness of the arc light in electrogas welding, and can perform good copying control. Therefore, the method of automatic copying control using a television camera can be used. The reliability is dramatically improved, and it can greatly contribute to automation and unmanned welding processes.

[Brief description of the drawings]

FIG. 1 is a plan view showing a shooting screen of a TV camera 20 shown in FIG. 4 and regions P1 to P5 set on the screen.

FIGS. 2A and 2B are views showing a state of a horizontal electrogas welding, in which FIG. 2A is a horizontal cross-sectional view at the center of a groove, FIG. 2B is a front view, and FIG.

3A and 3B are drawings showing a vertical electrogas welding state, in which FIG. 3A is a horizontal cross-sectional view, FIG. 3B is a front view, and FIG. 3C is a vertical vertical cross-sectional view.

FIG. 4 is an enlarged horizontal cross-sectional view at the center of a groove, showing a horizontal electrogas welding state and a TV camera 20 for photographing a welding wire portion.

5 is a graph showing a video signal level of the TV camera 20 shown in FIG. 4 when the welding arc has a standard brightness on the horizontal scanning line L1 shown in FIG. 1;

6 is a graph showing a video signal level when the welding arc of the TV camera 20 shown in FIG. 4 is short-circuited during the transfer of the droplet and disappears at the horizontal scanning line L1 shown in FIG. .

FIG. 7 is a view of the TV camera 20 shown in FIG. 4 at the horizontal scanning line L1 shown in FIG. 1 when the arc length of the welding arc is increased and the entire groove becomes bright by the arc flame; 5 is a graph showing a video signal level.

8 is a diagram showing the teaching pattern written in the internal memory of the microcomputer 10 shown in FIG. 16 and the input pattern on the screen taken by the TV camera 20 shown in FIG.
It is a graph which shows the brightness distribution of each corresponding pixel.

FIG. 9 is an enlarged plan view showing a region P2 shown in FIG. 1;

FIG. 10 is an enlarged plan view showing a region P1 shown in FIG. 1;

FIG. 11 is an enlarged plan view showing a region P3 shown in FIG. 1;

FIG. 12 is an enlarged plan view showing a region P4 shown in FIG. 1;

FIG. 13 is an enlarged plan view showing a region P5 shown in FIG. 1;

FIG. 14 is a plan view showing an example of an area setting in which wire position detection for a groove is inaccurate.

FIG. 15 is a left side view showing an outline of a mechanical section of a welding apparatus for implementing the present invention in one aspect, in which a steel plate has a vertical vertical section.

16 is a block diagram showing a configuration of an electric control system that drives the electric copying shaft 33 of the welding device shown in FIG.

17 (a) and 17 (b) show a material to be welded by electrogas arc welding in a horizontal position, where (a) is a front view and (b) is a side view. Opposite edges (a lower edge and an upper edge of the groove) of the lower plate and the upper plate of the material to be welded are substantially parallel.

FIGS. 18A and 18B show a material to be subjected to electrogas arc welding in a horizontal position, wherein FIG. 18A is a front view and FIG. 18B is a side view. Opposite edges of the lower plate and the upper plate of the material to be welded (the lower edge of the groove and the upper edge) are non-parallel.

FIGS. 19A and 19B show a material to be welded by electro-gas arc welding in a horizontal position, wherein FIG. 19A is a front view and FIG. 19B is a side view. Opposite edges of the lower plate and the upper plate of the material to be welded (the lower edge of the groove and the upper edge) are non-parallel.

FIG. 20 shows a material to be welded in electrogas arc welding in a vertical position, (a) is a front view, and (b) is a side view.

FIG. 21 is a plan view of a pseudo groove used in the first embodiment.

FIG. 22 is a plan view of a pseudo groove used in the third embodiment.

FIG. 23 is a graph showing a relationship between a groove width and a welding condition area set in the first embodiment.

FIG. 24 is a graph showing a relationship between a groove width and a welding condition area set in the second embodiment.

FIG. 25 is a graph showing a relationship between a groove width and a welding condition area set in the third embodiment.

FIG. 26 is a graph showing a relationship between a groove width and a welding condition area set in the fourth embodiment.

[Explanation of symbols]

1: chip 2: cooling sliding plate 3: groove 4: backing material 5: molten metal 6: arc 7: wire 8: bead 10: microcomputer 11: servo amplifier 12: copying shaft motor 13: image memory 13r: Comparative image memory 14: A / D converter 15: Limit switch 20: TV camera 21: VTR 22: Monitor T
VC 23: Distributor 31: Rail 32: Traveling trolley 33: Electric scanning shaft 34: Oscillating shaft motor 35: Rotating shaft

Claims (6)

[Claims] 1. A method for controlling a groove in an electrogas arc welding in a horizontal posture using image data obtained by simultaneously photographing a groove, a welding wire and a cooling sliding plate with a television camera, comprising: The average value of the brightness of the welding wire and the cooling slide plate is D1, and the average value of the brightness in the groove is D.
2. Assuming that the average value of the luminance of the lower plate surface and the cooling slide plate is D1, Dmin <D1 <D2 <Dmax (1) where Dmax is the maximum value that can be taken as image data corresponding to the luminance. A teaching pattern of welding wire and groove image data in an area corresponding to the first area including the welding wire on the comparative image memory so as to satisfy a minimum value that can be taken as image data corresponding to luminance. As the pattern K1, the image data of the lower plate surface, the cooling slide plate and the groove is written in the second area including the groove lower edge and the cooling slide plate as the teaching pattern K2 in advance before the copying control. Every time; from the image data taken by the television camera during the scanning control, an area I1 having a high correlation with the teaching pattern K1 is searched to determine a welding wire position, and an area I2 having a high correlation with the teaching pattern K2 is searched and opened. Determine the bottom edge position and determine Wire position and vertical position controls the welding torch and cooling the sliding plate in accordance with the lower edge position; groove tracking controlling method of electro-gas arc welding sideways posture, characterized in that. 2. A pseudo groove drawn so as to satisfy the expression (1) is photographed in advance before scanning control, and image data of a region including a welding wire is obtained as a teaching pattern K1 from the obtained image data. 2. The method according to claim 1, wherein the image data of the area including the lower edge and the cooling sliding plate is written as the teaching pattern K2 in the comparative image memory. 3. A method according to claim 1, wherein the groove, the welding wire and the cooling sliding plate are simultaneously imaged by a television camera, and the groove is controlled by electro-gas arc welding in a horizontal position. The average value of the brightness of the welding wire and the cooling slide plate is D1, and the average value of the brightness in the groove is D.
2. Assuming that the average value of the luminance of the lower plate surface and the cooling sliding plate is D1, and that the average value of the luminance of the upper plate surface and the cooling sliding plate is D1, Dmin <D1 <D2 <Dmax (1) However, Dmax corresponds to the first region including the welding wire on the comparative image memory so as to satisfy the following: Dmax: the maximum value that can be taken as image data corresponding to luminance Dmin: the minimum value that can be taken as image data corresponding to luminance In the second area including the lower edge of the groove and the cooling slide plate, the image data of the lower plate surface, the cooling slide plate and the groove are set in the second area including the lower edge of the groove and the cooling slide plate. The image data of the surface of the upper plate, the cooling slide plate and the groove as the teaching pattern K3 in the third area including the groove upper edge and the cooling slide plate is set in advance as a teaching pattern K2. Written before copying control; image taken by the television camera during copying control From the data, an area I1 having a high correlation with the teaching pattern K1 is searched to determine the welding wire position, and an area I2 having a high correlation with the teaching pattern K2 is searched to determine the lower edge position of the groove. The upper edge position of the groove is determined by searching the area I3 having a high correlation, and the vertical position of the welding torch and the cooling sliding plate is controlled according to the determined wire position and the lower edge position. A method according to claim 1, wherein the welding condition is switched in accordance with an edge position. 4. An image of a pseudo groove drawn so as to satisfy the equation (1) is taken in advance before copying control, and image data of a region including a welding wire is obtained as a teaching pattern K1 from the obtained image data. The image data of the area including the lower edge and the cooling slide plate is written in the comparative image memory as the teaching pattern K2, and the image data of the area including the upper edge and the cooling slide plate as the teaching pattern K3. 4. The method according to claim 3, wherein the groove tracking control for the electrogas arc welding in the horizontal position is performed. 5. A method for controlling a groove in electrogas arc welding in a vertical position using image data of a groove, a welding wire, and a cooling sliding plate simultaneously photographed by a television camera. The average value of the brightness of the welding wire and the cooling slide plate is D1, and the average value of the brightness in the groove is D1.
2. Assuming that the average value of the luminance of the left plate surface and the cooling sliding plate is D1, and that the average value of the luminance of the right plate surface and the cooling sliding plate is D1, Dmin <D1 <D2 <Dmax (1) However, Dmax corresponds to the first region including the welding wire on the comparative image memory so as to satisfy the following: Dmax: the maximum value that can be taken as image data corresponding to luminance Dmin: the minimum value that can be taken as image data corresponding to luminance In the second area including the left edge of the groove and the cooling slide plate, the image data of the left plate surface, the cooling slide plate and the groove is set as the teaching pattern K1 with the welding wire and the image data of the groove in the area. In the third area including the right edge of the groove and the cooling slide plate, the image data of the right plate surface, the cooling slide plate and the groove is set as the teaching pattern K3 in advance. Written before copying control; image taken by the television camera during copying control From the data, an area I1 having a high correlation with the teaching pattern K1 is searched to determine the welding wire position, and an area I2 having a high correlation with the teaching pattern K2 is searched to determine the groove left edge position. A search is made for an area I3 having a high correlation to determine the right edge position of the groove, and the left and right positions of the welding torch and the cooling sliding plate are controlled in accordance with the determined wire position, left edge position and right edge position. Groove tracking control method for electrogas arc welding in a standing posture. 6. A pseudo groove drawn so as to satisfy the expression (1) is photographed in advance before the copying control, and image data of a region including a welding wire is obtained as a teaching pattern K1 from the obtained image data. The image data of the area including the left edge and the cooling sliding plate is written as the teaching pattern K2, and the image data of the area including the right edge and the cooling sliding plate is written as the teaching pattern K3 in the comparative image memory. 6. The method according to claim 5, wherein the groove tracking control is performed in a vertical posture.