JPH0818133B2 - All posture automatic welding equipment - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to an all-position automatic welding apparatus capable of performing highly accurate welding in a stable arc state by accurately positioning a welding torch with respect to a groove to be welded.

[Prior art]

In the conventional automatic welding equipment used for welding the butt joints of pipe ends, it is necessary to mount the traveling rail that winds around the pipes parallel to and concentric with the welding line of the butt joint (groove) of the pipes. However, it was extremely difficult due to deformation of the tube. Therefore, an automatic welding technique has been developed in which the position of the welding torch is adjusted to follow the welding line of a pipe or the like while welding is being performed. As the automatic welding technique, a method of detecting the correction amount of the torch position in a system using an arc sensor, a method of detecting the shape of the welded portion by the coordinate system of the image screen of the image sensor (JP-A-58-181476), A method of capturing the shape of the welded part as image data and using it for groove tracking (Japanese Patent Publication No.
-155) etc.

[Problems to be Solved by the Invention]

However, in the method of detecting the correction amount using the above arc sensor, it is necessary to set a large number of control parameters in accordance with the welding conditions, the welding posture, etc. in order to make the arc sensor function with high accuracy. There was a problem of spending a lot of time on. Further, in the method disclosed in JP-A-58-181476, since the vertical position correction of the welding torch is not performed,
There is a problem in that the fluctuation of the extension occurs and the stability of the arc is lost. Further, the method disclosed in Japanese Examined Patent Publication No. 64-155 has a problem that it takes a long time for calculation because it requires calibration of the focal length. The present invention has been made to solve the above-mentioned conventional problems, and provides an all-position automatic welding apparatus having a simple configuration capable of accurately and quickly aligning a welding torch at an appropriate position with respect to a welded portion. The challenge is to provide.

[Means for Solving the Problems]

In an all-position automatic welding apparatus that positions a welding torch at a groove and moves along the groove to perform automatic welding, a video camera and a slit light source that move integrally with the welding torch are installed. The imaging surface of
Two-dimensional coordinates corresponding to the horizontal direction orthogonal to the groove and the vertical direction above and below the groove are formed, and
In the state where the optical axis of the video camera is intersected with the slit ray irradiated from the slit light source to the groove at a predetermined angle, a slit ray irradiation image showing the groove shape formed on the imaging surface of the video camera is displayed. Image processing is performed to calculate an actual two-dimensional coordinate value on the imaging surface for a specific position of the slit light source irradiation image, and the calculated actual two-dimensional coordinate value and the welding torch at the target position for the specific position. The difference between the preset reference position and the two-dimensional coordinate value is determined so that they match, and the welding torch, video camera, and slit light source are adjusted so that the difference between the two-dimensional coordinate values on the imaging surface becomes zero. By moving integrally in the vertical direction or the horizontal direction, and by matching the specific position of the slit ray image with the reference position, by enabling positioning to the target position on the welding torch, It is those that have achieved the serial task.

[Action and effect]

In the present invention, the specific position of the slit ray irradiation image representing the groove shape formed on the imaging surface of the video camera,
By moving the welding torch, video camera, and slit light source integrally until they match a predetermined reference position on the imaging surface, the welding torch can be accurately and quickly moved to an arbitrary position corresponding to the groove shape. Alignment can be done. Therefore, although the structure of the device is simple, the welding torch can be aligned not only in the lateral direction with respect to the groove but also in the vertical direction (vertical direction), so that the automatic welding of the groove is possible. Can be performed accurately and efficiently.

【Example】

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration view showing a main part of the all-posture automatic welding apparatus according to the first embodiment in use, and FIG. 2 is a schematic side view of the all-posture automatic welding apparatus. . The all-position automatic welding apparatus according to the present embodiment includes a welding torch 10 arranged above a steel pipe S to be welded, a laser / slit light source 12 and a CCD camera arranged substantially symmetrically with the torch 10 in the middle. ITV (Industrial Television) such as 1
4, and a control device (not shown) that drives the welding torch 10, performs image processing on the ITV 14, and the like. The welding torch 10, slit light source 12 and ITV 14 are all mounted on the welding head 16 shown in FIG. 2 (IT
Only V14 is shown), and these three members are integrally reciprocally movable in the vertical direction (vertical direction with respect to the groove) and the horizontal direction (direction orthogonal to the groove). And above ITV14
Are arranged so that the optical axis 14A intersects the irradiation axis 12A of the slit light source 12 at a predetermined angle. The welding head 16 is attached to the traveling rail 18. The running rail 18 is wound around the steel tube S _1, being adapted to rotate the running around the steel tube S _1, so that the welding head 16 is rotated around the steel tube S ₁ in accordance with the rotational travel Has been done. Therefore, the welding torch 10, the slit light source 12, and the ITV 14 mounted on the welding head 16 are rotated to the groove 20 which is a butt joint of the steel pipes S ₁ and S _{2 when} the traveling rail 18 rotates. Orbit along. Next, the operation of this embodiment will be described. First, the slit light source 12 irradiates the groove 20 with a slit light beam, the irradiation image at that time is imaged by the ITV 14, and the shape of the groove 20 as shown in FIG. 3 is formed on the imaging surface of the ITV 14. To form a slit ray irradiation image 22 corresponding to. In addition, A indicates an imaging area, and (x, y) coordinates indicating a target position of the welding torch 10 are formed in advance on the imaging surface, and the origin thereof corresponds to the target position. . The slit ray irradiation image 22 formed on the imaging surface is V
The character-shaped portion corresponds to the shape of the groove 20, and the lower end portion 22A thereof corresponds to the welding line 20A. In FIG. 3, the y-axis direction represents the amount of deviation between the groove 20 and the ITV 14 in the vertical direction (vertical direction) in the figure, and the x-axis direction represents the amount of lateral deviation, and the irradiation image 22 is on the x-axis. If it is, it means that the ITV 14 is at the target position in the vertical direction with respect to the corresponding groove portion, and if it is on the y-axis, it means that it is in the target position in the horizontal direction. . Here, the positional relationship in the vertical direction among the above relationships will be described in an easy-to-understand manner with reference to FIG. Considering now that the optical axis 14A of the ITV 14 and the irradiation axis 12A of the slit light source 12 intersect at a predetermined angle α, the irradiation point at the surface level of height H
P ₁ becomes the irradiation point P ₂ when the height becomes H ′, and it is deviated by δ ₁ from the P ₁ position. The position of the irradiation point P ₂ corresponds to the lower end 22A shown in FIG. 3, and the position P ₁ corresponds to the x-axis. Therefore, when welding the V-shaped groove,
Image analysis of the slit beam irradiation image 22, for example, the lower end
Calculate the 22A position (specific position) as (x, y) coordinate values,
Next, the ITV 14 or the like is moved in the horizontal direction and the vertical direction so that x = 0 and y = 0, and the lower end portion 22A is moved to the center of the imaging surface.
That is, by matching the origin (0,0), the welding line 2
The welding torch 10 can be naturally positioned at an appropriate welding position with respect to 0A. As described above, image analysis is performed on the irradiation image 22 obtained by the ITV 14, the welding head 16 is moved based on the result, and the specific position 22A of the irradiation image 22 is set to the origin (reference position on the imaging surface. ) To match the slit light source
The welding torch 10 that moves integrally with 12 and ITV 14,
A groove portion corresponding to the specific position, for example, the welding line 20.
It can be precisely aligned with the proper welding position for A. As a result, the welding line 20A between the traveling rail 18 and the groove 20
Even when and are not parallel, or when the traveling rail 18 is not concentric with the steel pipe, it is possible to perform automatic welding on the groove 20 accurately and quickly. Next, a second embodiment of the present invention will be described. This embodiment relates to the case of welding a groove having a root gap as shown in FIG. 5, and the basic structure of the apparatus is the same as that of the first embodiment except that the welding head is linearly movable along the groove. This is the same as in the first embodiment. The groove is formed in the inclined end face of the steel plate S ₃ and S ₄ located on both sides, and has a root gap width RG between the steel plate S ₃ and S _4. In addition, a prize 30 is arranged on the back side of the groove. When welding the groove, the welding torch 10, the slit light source 12 and the ITV 14 attached to the welding head 16 are arranged above the groove, and the welding torch 10 is moved following the groove. At that time, the welding torch 10 is positioned with respect to the groove basically in the same manner as in the case of the first embodiment. Therefore, in the following description of the present embodiment, the method of detecting the root gap width RG will be mainly described. Slits corresponding to the groove shape shown in FIG. 8 are obtained by irradiating the above-mentioned groove with a slit light beam, imaging the irradiation image with the ITV14 arranged as shown in FIG. 7, and performing image processing. A light beam irradiation image 32 is obtained. Here, the image processing will be described with reference to FIGS. 5 and 6. As shown in FIG. 5, when the groove is irradiated with the slit light beam, an irradiation image having the same width is formed in the groove, but in this irradiation image, the illuminance on the flat surface is larger than that on the slope. Figure 6 shows this relationship.
If the flat surface is the root gap of 30 (view A),
The illuminance when the slope is the groove on the right side (view B) is shown. If a certain threshold is set for the illuminance and the illuminance width corresponding to the threshold is taken as the irradiation image width, it is expressed that an irradiation image is formed that is wide in the flat portion and narrow in the slope portion as shown in FIG. it can. Irradiating a slit ray from the light source 12 to the groove, inputting an irradiation image formed in the groove to the ITV 14, performing the image processing as described above on the input, and an image having an illuminance of a threshold value or more. The slit beam irradiation image 32 shown in FIG. 8 is displayed as a region. In FIG. 8, by specifying points a and b, the root gap width RG can be calculated by the following equation. RG = (x value of point a)-(x value of point b) The points a and b are specified by extracting a region of interest centered on the root gap and performing steps (1) to (1) shown in FIG.
X max and x min are obtained by the procedure of (3), and they are respectively taken as the x values of the points a and b (for convenience, the root gap is shown in the vertical direction in FIG. 9 and subsequent figures). At that time, in the binarization process of step (2), when the illuminance threshold is set to v or v ′ as shown in FIG. 10B, the illuminance at the CC position in FIG. The width becomes RG or RG ′, and the measurement accuracy depends on how the threshold is set. Therefore, the threshold is set appropriately. In addition, in order to improve the reliability of the measurement, in addition to the binarization processing, image degeneration / expansion processing as shown in steps (1) to (3) in FIG. 11 is performed, and in step (3). The point a may be obtained. Further, it is possible to further improve the measurement accuracy by repeating the above-described image shrinkage / expansion process several times. In the detection of the root gap RG described in detail above, it is necessary to accurately match the focus of the ITV 14 with the root gap position, that is, the upper surface of the dough 30. That is, in the optical system shown in FIG. 12, if the subject M is imaged at the m position when the lens is focused, the subject M'is imaged at the m'position if the focus is properly performed. If they are not aligned, the image is formed in the out-of-focus state at the m ″ position and the boundary of the image becomes vague. As a result, the phenomenon shown in the partial view of FIG. 13 corresponding to FIG. 10 (B) appears. FIG. 13 (A) shows the illuminance curve in the normal case where the image is in focus, and FIG. 13 (B) shows the illuminance curve in the case of defocused image. Then, the point a to be specified shown in FIG. 9A is changed to the point a ′ shown in FIG.
It will be reduced to RG '. Therefore, in order to improve the measurement accuracy, focus adjustment (ITV14 alignment) accuracy is important. In the welding device of the present embodiment, the same machine as the first embodiment,
(X, y) coordinates are formed on the image pickup surface of the ITV14 (not shown in FIG. 8), and the y coordinate value and the x coordinate value are the amount of vertical and horizontal displacement between the target and the ITV14. By aligning the specific position of the slit light beam irradiation image 32 corresponding to the target with the x coordinate axis, the focusing can be accurately performed. Therefore, in the case of detecting the root gap RG of the groove shown in FIG. 5, by positioning the ITV 14 so that the root gap, that is, the upper surface of the metal 30 is aligned with the x coordinate axis on the imaging surface, The root gap can be detected in focus, and the root gap width RG can be obtained with high accuracy. The information about the groove including the root gap RG thus obtained is stored in the storage unit of the control device and is reflected in the next welding operation. Further, the welding apparatus of the present embodiment, when the specific position of the slit light beam irradiation image 32 corresponding to the welding target position is made coincident with the coordinate origin (0,0) on the imaging surface, the welding moves integrally with the ITV14. The torch 10 is adjusted so as to have an appropriate arrangement with respect to the welding target position. Therefore, the specific position of the slit beam irradiation image 22 corresponding to the welding target position of the groove is obtained by image analysis, ITV14 is moved until the coordinate position matches the coordinate origin (0,0), and the match By operating the welding torch 10 at this position, it is possible to accurately perform the target welding at the welding target position.
Then, by repeating the above-mentioned welding operation sequentially for the target position of the groove, it is possible to automatically perform high-precision welding matching the shape of the groove. Although the present invention has been specifically described above, it is needless to say that the present invention is not limited to the one shown in the above-mentioned embodiment, and various modifications can be made without departing from the scope of the invention.

[Brief description of drawings]

FIG. 1 is a schematic configuration view showing a main part of the all-position automatic welding apparatus according to the first embodiment which is in a use state, and FIG. 2 is a schematic side view of the all-position automatic welding apparatus. FIG. 3 is a schematic explanatory view showing the image pickup surface of the ITV, FIG. 4 is a schematic explanatory view for explaining the operation of the embodiment, and FIG. 5 shows a groove to which the second embodiment is applied. 6 is a perspective view showing the illuminance curve in the irradiation image formed in the groove of FIG. 5, and FIG. 7 is an explanatory view showing a state in which the groove is imaged by the ITV. FIG. 8 is an explanatory view showing a slit ray irradiation image in which the image formed on the image pickup surface of the ITV is represented as an illuminance region exceeding a threshold value, and FIG. 9 is an explanatory view showing a procedure for specifying a root gap width, FIG. 10 is an explanatory diagram showing the relationship between the root gap width and the illuminance threshold value, and FIG. 11 is a procedure of image degeneration / expansion processing. Explanatory view showing, Fig. 12 is an explanatory diagram showing a relationship between the subject and the imaging in the optical system, FIG. 13 is an explanatory view showing a change of illuminance by Pinto condition. 10 …… Welding torch, 12 …… Slit light source, 14 …… ITV, 1
8 …… Traffic rail, 20 …… Groove, 22,32 …… Slit beam irradiation image.

Claims (1)

[Claims] 1. An all-posture automatic welding apparatus that positions a welding torch at a groove and moves along the groove to perform automatic welding, in which a video camera and a slit light source that move integrally with the welding torch are installed. The image pickup surface of the video camera is formed with two-dimensional coordinates corresponding to the horizontal direction orthogonal to the groove and the vertical direction above and below the groove, and the optical axis of the video camera is In the state where the slit light beam irradiated from the slit light source to the groove intersects at a predetermined angle, a slit light beam irradiation image representing the groove shape formed on the imaging surface of the video camera is image-processed, and the slit light source irradiation is performed. An actual two-dimensional coordinate value on the imaging surface is calculated for the specific position of the image, and the calculated actual two-dimensional coordinate value and the welding torch for the specific position match the target position. , The difference between the preset reference position and the two-dimensional coordinate value is obtained, and the welding torch, the video camera and the slit light source are integrated so that the difference between the two-dimensional coordinate values on the imaging surface becomes zero. An all-position automatic welding apparatus, which is capable of positioning the welding torch at a target position by moving the welding beam in a vertical direction or in a horizontal direction and matching a specific position of the slit ray image with the reference position.