JPH08276270A - Copy welding method - Google Patents

Abstract

PURPOSE: To enable the accurate copy welding by extracting the coordinates of the feature point of the groove through the approximate processing of the light cutting image, and putting the initializing set value at the position of the center of gravity of the image of the molten pool image to correct the position of the wire tip of a welding torch. CONSTITUTION: A welding truck 2 is horizontally moved along a traveling rail 4 which is installed approximately parallel to the joint groove of a material to be welded. A welding torch 3 supported by a welding arm 5 is arranged at the lower part of the welding truck 2, and a longitudinally moving means 6, a vertically moving means 7, and a horizontally turning means 8 are operated by a welding equipment control device 9. A sensor unit 11 detects the groove shape or the position of the wire tip of the welding torch 3, and is provided with a laser beam irradiation equipment and a photographing equipment for the image of the molten pool. An image processor 15 extracts the coordinates of the feature point of the groove from the light cutting image through the straight line and curved line approximation, and the wire tip position is calculated by putting the initializing value to the point of the center of gravity of the image of the molten pool, and controlled by the welding equipment control means 9. The accurate copy welding can be achieved thereby.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a profile welding method and apparatus for welding while following a joint groove in a lateral position or a downward position, and in particular, it automatically performs a welding profile using a laser beam and an optical system. The present invention relates to a copy welding method.

[0002]

2. Description of the Related Art Since the strength of the furnace body of a blast furnace depends on the strength of the steel shell, it is desired to perform high-quality steel shell welding in the blast furnace repair work. However, in recent years, it is difficult to secure a skilled welder, and since the blast furnace iron shell is a thick plate, automation of the iron shell welding has been attempted in order to make the welding quality uniform and improve the welding efficiency.

Conventionally, as this kind of automation technology, various technologies have been proposed for automatically performing welding copying using a laser beam, an optical system, etc., for example, Japanese Patent Laid-Open No. 2-3428.
Invention relating to the "arc welding imaging method" disclosed in Japanese Patent Publication No. 0 (hereinafter referred to as "Citation 1") and Japanese Patent Publication No.
The invention relating to the "welding position detecting device" disclosed in Japanese Patent Publication No. -16226 (hereinafter referred to as "Citation 2") can be mentioned.

In the reference example 1, "current from the welding power source is 1
The operation of shutting off for / 2000 to 1/10 seconds is repeated, and the operation of opening and closing the shutter of the television camera is performed during the current shutoff time in synchronization with the above time. Is disclosed.

That is, the reference example 1 is intended to photograph the arc, the pool, the bead and the groove satisfactorily by cutting off the welding current for a short time so that the arc light is dimmed. is there.

Further, in the second reference, "While observing an arc with an observation optical system, a linear converging light beam is irradiated on the groove surface near the arc point, and the reflected light is reflected by the observation optical system. By arranging the optical system so that it is observed at the same time as the arc observation, the arc image and the groove light cutting image are directly brought into the field of view of the two-dimensional optical position detector of one observation optical system. The images are detected at the same time. "

That is, in the reference example 2, by arranging optical systems for irradiating the linear condensed light beam and for observing, and detecting the arc image and the groove light cutting image directly in the visual field of the observing optical system. The aim is to improve the welding copying accuracy and downsize the apparatus.

[0008]

By the way, in the reference example 1, since the position of the wire tip of the welding torch cannot be accurately detected, the shape of the groove and the bending of the wire tip due to welding heat are not detected. There is a problem that it is difficult to cope with and precise copy welding cannot be performed.

Further, in the second reference example, the arc light is blocked by the filter, but it is still difficult to completely remove the influence. Furthermore, when performing image processing, it was difficult to remove the influence of welding spatter scattered in the image.

Therefore, in order to avoid the influence of arc light and spatter, it is necessary to separate the laser irradiation portion and the welding portion to some extent, but on the other hand, if the distance between them increases, thermal deformation of the groove and the tip of the wire will occur. However, there is a problem in that it is difficult to cope with the bending and the like, and it is impossible to perform precise copy welding.

In view of the above problems, an object of the present invention is to relatively reduce the arc light and the molten pool radiation light with respect to the high-power pulse laser linear light, and also to obtain the thermal deformation of the groove and the wire. Even if the laser irradiation part and the welded part are brought close to each other to cope with bending of the tip, etc., the influence of arc light and spatter can be completely avoided, and a profile welding method capable of performing extremely precise welding copying is provided. To provide.

[0012]

In order to achieve the above object,
The profiling welding method according to the present invention, when detecting a decrease in welding voltage, a laser linear light is emitted from a laser light irradiation device that generates a high-power pulse laser to a groove located immediately in front of the traveling direction of the welding torch. At the same time as irradiating, the high-speed electronic shutter of the imaging device is opened, the light cut image and the molten pool image are picked up through the interference filer, and the light cut image is approximated to extract the groove feature point coordinates. The wire tip position is calculated by adding an initial setting value to the center of gravity of the molten pool image, and the wire tip position of the welding torch is corrected based on these values.

In the above structure, the decrease of the welding voltage occurs when the droplet is short-circuited during short-circuit arc welding or when the power supply current is interrupted during pulse arc welding.

Preferably, the high power pulse laser is
The output is set to 1 to 200 W.

Preferably, the laser linear light is
The groove is positioned 30 to 100 mm forward of the welding torch in the traveling direction.

Furthermore, it is preferable that the shutter speed of the high-speed electronic shutter is set to 0.1 to 1 msec.

Preferably, the interference filter is set to have a wavelength of the laser beam of ± 10 nm or less.

In addition, preferably, the light section image and the molten pool image are picked up a plurality of times, each image is binarized, and the groove feature point coordinates are extracted by a logical product calculation process. .

Preferably, the coordinate difference between the center of gravity and the center of the molten pool image is calculated, and the welding conditions are controlled based on this calculated value.

Further, preferably, when the ratio of the average value of the welding currents before and after the groove becomes a predetermined value or more, it is judged that the wire tip position is at the groove back, and based on this. The position of the wire tip of the welding torch is corrected.

[0021]

According to the above-described structure of the profile welding method, when the decrease in the welding voltage is detected, the linear laser light is emitted from the laser light emitting device for generating the high output pulse laser, and the high speed electronic shutter of the image pickup device is operated. The light section image and the molten pool image are taken by opening. This is to emit a laser beam in an extremely short time and to open the electronic shutter only at that moment to increase the intensity of the laser beam and relatively reduce intense arc light, molten pool radiation, etc. The effect is removed.

The above-mentioned decrease in welding voltage occurs at the time of transition to a droplet short circuit in short-circuit arc welding or when the power supply current is cut off in pulse arc welding, and the arc light is reduced.

Further, the laser linear light of the high output pulse laser is applied to the groove located immediately in front of the direction of travel of the welding torch. This is to bring the laser light irradiation part and the welding part close to each other so as to cope with the shape deformation of the groove due to welding heat. Even if the laser light irradiation part and the welded part are brought close to each other in this way, when the welding current is reduced and the arc light is reduced, the relative intensity of the laser light is changed by synchronizing the high-power pulse laser and the high-speed electronic shutter. Since the optical cutting image and the molten pool image are picked up by the image pickup device through the interference filter which raises the relative intensity of the laser beam, it is necessary to completely avoid the influence of arc light, molten pool radiation, etc. You can

The groove feature point coordinates are extracted by the approximation process, that is, the linear approximation and / or the curve approximation from the light section image thus taken, and the initial setting value is added to the center of gravity of the molten pool image. If the wire tip position is calculated, the calculated value is compared with the groove feature point coordinates, and the deviation is added as a correction value to the torch target position, precise welding copying can be performed.

In particular, the pulse laser output is 1 to 200 W.
Although it depends on the pulse width, it is necessary to have a high output capable of sufficiently capturing an image with a high-speed electronic shutter. That is,
If it is less than 1 W, it is difficult to capture an image with the high-speed electronic shutter, and if it exceeds 200 W, it is not practical.

If the laser linear light is applied to a groove located 30 to 100 mm forward of the welding torch in the traveling direction, thermal deformation of the groove can be surely dealt with. The reason why it is set to 30 to 100 mm forward of the welding proceeding direction is that if it is less than 30 mm, the influence of the arc light is too strong, and if it exceeds 100 mm, it becomes difficult to deal with shape deformation of the groove due to welding heat. .

Further, the shutter speed of the high-speed electronic shutter is set to 0.1 to 1 msec in order to perform high quality imaging in consideration of the relationship with the output of the pulse laser. That is, an electronic shutter having a shutter speed of less than 0.1 msec is not practical, and if it exceeds 1 msec, the imaging time is too long in relation to the pulse laser.

The reason why the interference filter is set to a wavelength of the laser beam of ± 10 nm or less is that the wavelength of the semiconductor laser has a variation of about ± 10, and therefore the filter needs to have the same half width.

The light cutting image and the arc light image are picked up a plurality of times, each image is binarized, and the groove feature point coordinates are extracted by the logical product calculation process. This is because a large amount of noise image components such as the above is included, so that these noises appearing at unspecified locations are removed by performing a logical product operation process between the binarized images of a plurality of surfaces.

Further, the coordinate difference between the center of gravity and the center point of the molten pool image is calculated, the deformation of the molten pool shape can be known from this calculated value, and the penetration depth is calculated from the area and width of the molten pool. By doing so, it becomes possible to perform fine control of welding conditions.

Then, when the ratio of the average values of the welding currents before and after the groove exceeds a predetermined value, it is determined that the wire tip position is inside the groove. That is, the average value and standard deviation of the welding current when moving from the front to the back of the groove are taken, and if the standard deviation is within a certain set value, the average value is recorded. Next, take the average value and standard deviation of the welding current at the back of the groove, compare the average value recorded when the standard deviation is within a certain set value with the average value at the back of the groove, and then calculate the ratio. If it is within a certain set value, it is determined that the wire tip position is inside the groove. Based on this determination, precise welding copying is performed.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the copy welding method according to the present invention will be described below in detail with reference to the accompanying drawings. The profile welding method according to the present embodiment is performed using a profile welding apparatus as shown in FIG. As shown in the figure, the welding carriage 2 of the profile welding apparatus 1 is configured to travel along a traveling rail 4 while supporting the welding torch 3.

The traveling rail 4 is installed substantially parallel to the joint groove of the object to be welded (not shown) in a sideways posture or a downward posture. Therefore, the welding carriage 2 travels substantially horizontally along the longitudinal direction of the traveling rail 4. A straight traveling rail and an arcuate traveling rail can be used for the traveling rail 4, and an object to be welded having a curved surface can also be a welding target. Therefore, if the arcuate traveling rail is used, the copy welding apparatus 1 of the present embodiment can be applied to the welding of the circumferential joint of the blast furnace iron shell.

A welding torch 3 is arranged below the welding carriage 2 and supported by a welding arm 5. The welding arm 5 is connected to the welding carriage 2 via a front-back movement means 6, a vertical movement means 7 and a horizontal rotation means 8 arranged on the welding carriage 2.

The front-rear moving means 6 moves the welding torch 3 in the plate thickness direction of the object to be welded, and the vertical moving means 7 moves the welding torch 3.
Is moved in the vertical direction, and the horizontal rotating means 8 moves the welding torch 3
For rotating in a horizontal plane, each of which is connected to the welding machine controller 9.

Therefore, the front-rear moving means 6 and the up-down moving means 7
The horizontal rotation means 8 is operated by a gear mechanism (not shown) driven by a motor according to the rotation speed / position calculated by the welding machine control device 9. In particular, the horizontal rotation means 8 controls the rotational speed and position of the motor so that the axis of curvature of the workpiece and the axis of the welding torch 3 are always parallel.

That is, the welding torch 3 is moved by the forward / backward moving means 6.
The welding torch 3 can be moved up and down by the up-and-down moving means 7, and by controlling these by the welding machine control device 9, the aim of the welding torch 3 can be freely decided up, down, left and right. it can.

Further, the horizontal rotating means 8 can rotate the welding torch 3 in a horizontal plane. Therefore, when the traveling rail 4 and the object to be welded have different curvatures, the horizontal rotating means 8 is operated so that the direction of the welding torch 3 can always be maintained in a constant direction with respect to the object to be welded. As a result, several types of traveling rails 4 can be used according to the curvature of the workpiece.
Therefore, it is possible to weld the objects to be welded having different curvatures with one type of traveling rail 4.

The torch mounting portion of the welding arm 5 is provided with vertical rotating means 10 having an arc shape. The vertical rotating means 10 is means for rotating the welding torch 3 in the vertical plane, and is operated by a gear mechanism (not shown) driven by a motor according to the rotation speed and position calculated by the welding machine control device 9. Is made like. Since the welding torch 3 is rotated by the vertical rotating means 10 while drawing an arc around the welding wire tip (welding arc point),
Welding torch 3 in the vertical plane without the welding arc swinging
The tilt angle of can be changed.

A sensor unit 11 shown in FIG. 2 is connected to the welding carriage 2 so as to detect the groove shape of the joint and the wire tip position of the welding torch 3. As shown in the figure, in the sensor unit 11,
A laser irradiation device 12 that irradiates the joint groove with laser linear light, and an imaging device 13 that captures a light section image of the laser linear light and a molten pool image are housed.

The laser irradiation device 12 has a wavelength of 680 ± 10.
It is composed of a semiconductor pulsed laser with a wavelength of 1 nm and an output of 1 to 200 W, and a collimator lens and a cylindrical lens for linearizing the laser light are used.

In this embodiment, the wavelength of the laser light is set to 68.
The reason why it is set to 0 nm is as follows. That is,
The spectrum of the arc light is Fe or shield gas (Ar
Etc.) close to the characteristic spectrum intensity distribution of 600 to 700
The intensity decreases at wavelengths near nm. In addition, the spectrum of the molten pool radiation increases in intensity as the wavelength becomes longer from the visible light to the infrared light wavelength range. Therefore, in this embodiment, the wavelength of the laser light used for measurement is set to 680 nm, which is less likely to be affected by the arc light and the molten pool radiation.

The output of the pulse laser is set to 1 to 200 W because it depends on the pulse width, but it is necessary to have a high output capable of sufficiently capturing an image with a high-speed electronic shutter described later.
An output of 35 to 50 mW is usually used for the copy welding.

Further, the image pickup device 13 picks up a light section image and a molten pool image, but after a delay of about 1 μS with respect to a trigger signal from the outside, a high-speed electronic shutter (not shown) which opens and closes in an extremely short time. ) Equipped with a CCD camera.

The use of a CCD camera as the image pickup device 13 is advantageous in that the CCD camera is smaller and easier to handle than an image pickup tube camera, and there is no problem such as burning, and a two-dimensional CCD element is used. In this case, compared to the one-dimensional type, mechanical laser scanning is not required, so there are few failures, and two-dimensional information is handled, so it is easier to perform image processing such as shape recognition. Because there are advantages.

Further, the shutter speed of the high speed electronic shutter is set to 0.1 to 1 msec. The shutter speed is set to 0.1 to 1 msec in order to perform high quality imaging in consideration of the relationship with the output of the pulse laser.

An interference filter 14 having a wavelength of laser light (680 nm) ± 10 nm is provided in front of the image pickup lens 13a of the image pickup apparatus 13. The wavelength of the interference filter 14 is set to a laser wavelength of ± 10 nm because the interference filter is used to increase the relative intensity of the laser light, but the wavelength of the semiconductor laser varies by about ± 10 nm. This is because the filter 14 also needs a similar half width.

Further, the image pickup device 13 is connected to an image processing device 15 for processing the picked-up light section image and the molten pool image. This image processing device 15 extracts the coordinates of the groove feature points from the light section image by approximation processing, that is, by linear approximation and / or curve approximation, and adds an initial setting value to the center of gravity of the molten pool image to determine the wire tip position. Is a calculation means for calculating The image processing device 15 is also connected to an image capture controller 16 that monitors whether the welding voltage drops below a set threshold value and controls the image capture position.

The image processing device 15 and the image capturing control device 16 are connected to the welding machine control means 9 for controlling the welding torch 3 based on the calculated value of the image processing device 15 and correcting the wire tip position. There is.

Further, the laser irradiation device 12 is positioned within the sensor unit 11 so as to irradiate the laser linear light perpendicularly to the groove located 30 to 100 mm forward of the welding torch 3 in the traveling direction. Has been done. Further, the imaging device 13 uses the welding torch 3 for the light section image and the molten pool image.
The positions are set in the sensor unit 11 so that the images are respectively captured from the front diagonally.

Next, the profile welding method of this embodiment, which is performed using the profile welding apparatus 1, is performed as follows. The profile welding method according to the present embodiment is used, for example, when welding a groove of a blast furnace iron shell, and is performed by a 1-pass-1 rare-torch angle changing lateral welding method. At that time, the copy welding apparatus 1
The welding carriage 2 is moved along the traveling rail 4, and the welding machine controller 9 controls the longitudinal movement means 6, the vertical movement means 7, the horizontal rotation means 8 and the vertical rotation means 10 by four axes to perform welding welding torch 3. By performing the weaving operation, the automatic copy welding is performed.

In the copy welding method of this embodiment, the welding voltage is monitored by the image capturing control device 16 during the 1-pass 1-rare welding, and when the decrease is detected, a trigger pulse is emitted to the laser irradiation device 12 and the imaging device. Output to 13.

This decrease in the welding voltage occurs at the time of transition to the droplet short circuit in the short-circuit arc welding or at the time of shutting off the power supply current in the pulse arc welding, and the arc light is reduced. For example, in the case of mag welding, when the welding current exceeds 200 A, the droplets of the welding wire are in a spray transfer state, and the arc light is not reduced. Therefore, as shown in FIG. 3, by dropping the welding current to 200A or less at a position where the weaving locus W is in the groove front part AB (A is a welding current decrease start point, B is a welding current decrease end point), Arc light is reduced to enable measurement.
The reason why the welding current is reduced at the positions of the groove front portions A to B is that the welding quality is relatively unaffected.

By entering the droplet short circuit transition state,
At the moment when the arc light is reduced in the vicinity of the position of A ′, that is, the welding voltage is monitored by the image capturing control device 16, a trigger pulse is output to the laser irradiation device 12 and the imaging device 13 at the moment when the welding voltage falls below the set threshold value. While irradiating the groove with the pulsed laser linear light, the high-speed electronic shutter of the image pickup device 13 provided with the interference filter 14 is opened to pick up a light section image and a molten pool image. The wavelength of the interference filter 14 is set to the wavelength of the laser light (680 nm) in order to avoid the influence of the intense arc light.
nm) ± 10 nm or less, and the imaging device 13
The light section image and the molten pool image captured by
Is input to

That is, as shown in FIG. 4, assuming that the groove front voltage set value is Va and the threshold value is 0.6 Va, a trigger pulse is generated in synchronization with the trailing edge of the signal for which the welding voltage V ≦ 0.6 Va. Outputs TP (negative logic for 1 ms or more). After a delay of about 1 μS with respect to this trigger pulse TP, the imaging device 1
The high-speed electronic shutter 3 is opened within the set time.

More specifically, as shown in FIG. 5, the short circuit period is at the front part of the groove where the welding current is reduced, but the period when the image pickup device 13 is stopped in the welding direction can be captured. (Enable).

Then, as shown in FIG. 6, the welding power source 1 is controlled by the image capture controller (external trigger controller) 16.
The welding voltage V of No. 7 is monitored, and the welding voltage V has a threshold value of 0.6.
When it drops to Va, the trigger pulse TP is generated in synchronization with the fall.

The trigger pulse TP is the camera controller 1
R.8. R. At the same time as input (reset / restart) is entered and the high-speed electronic shutter is released, the host computer 19
When an interrupt is generated at the time, and it is the enable period, the image processing device 15 is instructed to capture an image. The welding power source 17 is connected to a host computer 19 via a welding machine controller (robot controller) 9.

On the other hand, in the pulse arc welding, the droplet transfer state is changed to the spray transfer state by applying a pulsating flow, but the welding voltage drops when the current is cut off. Therefore, even when the pulse arc welding is adopted, it is possible to monitor the welding voltage by the image capturing control device 16 and output the trigger pulse to the laser irradiation device 12 and the image pickup device 13 when the decrease thereof is detected. .

Next, the laser irradiation device 12, which has received the trigger pulse from the image capture control device 16, irradiates the groove located immediately in front of the welding torch 3 in the traveling direction with the laser linear light of the high-power pulse laser. .

Specifically, the laser irradiating device 12 is 30 to 100 forward from the welding point of the welding torch 3 in the welding advancing direction.
1 to 200 perpendicular to the groove at a position separated by about mm
The pulsed laser linear light of W output is irradiated. If the output of the pulse laser is set to 1 to 200 W, if it is less than 1 W, it is difficult to capture an image with a high-speed electronic shutter.
This is because if it exceeds W, it is not practical.

Further, the irradiation position of the pulsed laser linear light is set 30 to 100 mm forward of the welding torch 3 in the advancing direction because the influence of the arc light is too strong when the distance is less than 30 mm and exceeds 100 mm. This is because it is difficult to deal with shape deformation due to welding heat in the case of a groove with a very thick plate such as a blast furnace iron skin.

On the other hand, the image pickup device 13 which has received the trigger pulse in synchronization with the laser irradiation device 12 opens and closes the high-speed electronic shutter, and through the interference filter 14, picks up the light section image and the molten pool image. The shutter speed of the high-speed electronic shutter is set to 0.1 to 1 msec as described above. The shutter speed is set to 0.1 to 1 msec because an electronic shutter having a shutter speed of less than 0.1 msec is not realistic, and if it exceeds 1 msec, the imaging time is too long in relation to the pulse laser. For example, when the output of the pulse laser is set to 1 W, the shutter speed of the high speed electronic shutter is set to 500 μsec.

The interference filter 14 is set to a wavelength of the laser light (680 nm) ± 10 nm or less in order to avoid the influence of intense arc light and molten pool radiation, and the light picked up by the image pickup device 13 is used. The cut image and the molten pool image are input to the image processing device 15.

As described above, in this embodiment, when the welding current is reduced and the arc light is reduced, the relative intensity of the laser light is increased by synchronizing the high output pulse laser and the high speed electronic shutter, and Since the light section image and the molten pool image are captured by the image capturing device through the interference filter 14 that increases the relative intensity of the laser light, it is possible to completely avoid the influence of arc light, molten pool radiation light, and the like. Therefore, the single image pickup device 13 can capture the light section image and the molten pool image in the same visual field.

Next, since only the image pickup by the interference filter 14 or the high-speed electronic shutter is not sufficient for image measurement,
Image quality is improved by image processing. That is, the imaging device 13 captures the light section image and the molten pool image a plurality of times. The light section image and the weld pool image are captured multiple times because the light section image and the weld pool image during welding contain a lot of noise image components such as spatters in the image. This is to remove these noises appearing at unspecified locations by performing a logical product operation process between the (black and white / grayscale process) images.

Specifically, the light section image and the molten pool image captured at the first time are recorded in the image memory, the light section image and the molten pool image captured at the second time are fetched, and the binary image is stored together with the recorded image. After performing the smoothing process and the smoothing process, a logical product (AND) process for each pixel is performed between the two images to remove the noise image. If necessary, the same logical product operation is performed on the light section image and the molten pool image captured for the third time.

Next, for the AND-processed image, isolated points
Remove end points. That is, after the 3 × 3 smoothing filter process (smoothing operator) is performed on the binarized image, the second binarization process is performed. X-direction differential processing (difference operator) is performed on the smoothed binary image to perform line image conversion. Then, the linear approximation method is used to extract the in-groove feature points (first layer) shown in FIG. 7A, and three-dimensional coordinate conversion is performed on the feature points to obtain desired coordinate values. For the second and subsequent layers, points on the extended line of the straight line portion are extracted as feature points as shown in FIG. 7B.

Specifically, in order to detect the groove feature points, a linear approximation method and / or a curve approximation method called a division / synthesis method (start point / end point approximation) and a tracking method (cone intersection method) are used. calculate. The detailed contents of this approximation process are described in "Recognition and Understanding of Drawings", by Sho Osawa et al., Shokoido Co., Ltd.

That is, the groove feature points are extracted based on the feature point extraction flow shown in FIG. As shown in the figure, first, in step (ST) 1, set the search window,
The start and end points in the window are detected (ST2).

Specifically, as shown in FIG. 9, when P1, P2, and P2 'are detected by the tracking method, Ps (start point) and Pe (end point) are determined, and pixels are determined by the search window shown in FIG. To track. That is, from Ps,
Using the downward search window shown in 0 (a), Pe
From here, the upward search window shown in FIG.

Then, the pixel connection state in the vicinity viewed from the pixel C is checked, and the pixel having the highest priority is set as the next tracking pixel. Downward priority is PD>PRD>PLD> PR
> PL, and the upward priority is PU>PRU> PLU
>PR> PL.

When the connection is broken, the search window is shifted as shown in FIG. That is, the window center pixel C is shifted to the positions of C1, C2 and C3, and a window having the center C newly is generated.
In this case, the priority order is C1>C2> C3. If the connection cannot be found even after shifting, the original center pixel is set as the singular point.

After detecting a pixel in the search window, it is checked whether or not it fits in a straight line. First, the pixel is traced downward from Ps, and P1 is obtained as follows (S
T3). First, in step 3, as shown in FIG.
The starting point pixel Ps and the pixel Q1 to be tracked next are selected. In this case, Q1 is not necessarily the next connected pixel. Further, two tangent lines are drawn from Ps with respect to a circle having a center of Q1 and a radius of r, and the enclosed area is S1. Note that Q1 is determined by the value of the radius r, and the line segment PsQ1> r.
Then, Q1 is set to Qi, S1 is set to Si, and the next step 3
Go to.

In step 3, the pixel Qi + 1 connected next to Qi is searched in the search window, and this is the region Si.
If so, proceed to step 3. On the other hand, if Qi + 1 does not exist or does not exist in the region Si, Qi is set as the feature point P1.

In step 3, two tangent lines are drawn from Ps with respect to a circle having a radius r and a center Qi + 1. Then, the region surrounded by these is set to Si + 1, the common region of Si and Si + 1 is set to Si, and Qi + 1 is set to Qi, and the process returns to step 3.

Similarly, the pixel is tracked upward from Pe,
P2 is obtained (ST4). This process is the same as step 3 above.
Repeat steps similar to. However, the upward search window is used.

Next, as shown in FIG. 13, P0 is detected. However, since the line image is often interrupted in the deep part of the groove, the tracking method cannot be used, so the division / synthesis method (start point / end point approximation method) is performed.
To use. A pixel having the maximum Euclidean distance with respect to the line segment having P1 and P2 obtained by the tracing method as the start point and the end point is obtained, and this is designated as P0 (ST5, ST6). That is, P
The coordinates of 1, P2 are (X1, Y1), (X2, Y2)
Then, the line segment P1P2 from the pixel Pj (Xj, Yj)
The distance Ej to is expressed by the following equation.

[Equation 1]

As shown in FIG. 14, the X direction is WX.
The distance calculation from 1 to WX2 and from Y1 to Y2 in the Y direction is performed. Then, in order to avoid the influence of noise or the like, pixel detection is performed from the forward direction and the reverse direction, and only those whose coordinates match are valid. In this case, it is 1 pixel / 1 LINE due to the X-direction differentiation.

Next, if it is the first welding (ST7), the radius r is set to a large value and P is set by the tracing method with Pe as the starting point.
2'is detected (ST8). The formula of the tangent line from the point Ps (Xs, Ys) to the circle with the radius r centered on the point Pi (Xi, Yi) is as follows.

[Equation 2] Further, since the point (a, b) is in the area surrounded by the tangent formula, the following formula is established.

(Equation 3)

Next, as shown in FIG. 15, P0 'is detected. That is, the line segment P1P2 and P
An approximate straight line for 2′P0 (passes through P1 and P2 ′) is obtained, and the intersection is defined as P0 ′ (ST9, ST10). That is, with P1 as the starting point, pixels are detected up to P0 (the same as in the division / synthesis method, the forward direction and the reverse direction are not used, and the search window is not used), and it is checked whether or not it fits on a straight line as follows. .

First, in step 9, a circle with a radius r0 centered at P0 is drawn, and two tangent lines are drawn from P1 to this circle. Then, it is checked whether or not the pixel Q1 next to P1 is in the area S0 surrounded by the tangent line. Q this
Repeat until 1 is detected. However, line segment P0Q1>
r, used in step 9.

In step 9, two tangent lines are drawn from P1 to a circle having a center of Q1 and a radius of r, and the enclosed area is S1.
And Then, Q1 is set to Qi and S1 is set to Si, and the process proceeds to the next step 9.

In step 9, the next pixel Qi + 1 of Qi + 1
, And if this is in the region Si, go to step 9. On the other hand, if it is not in the area Si, step 9 is repeated. The Y direction is Y0 (Y of P0
(Coordinates), the process proceeds to step 9 described later.

In step 9, a circle of radius r is drawn centering on Qi + 1, and two tangent lines are drawn from Ps to this circle.
The area surrounded by these is defined as Si + 1, and Si and Si + 1
Of the common area of Si and Qi + 1 as Qi, step 9
Return to

In step 9, a linear equation of the line segment P1Qi is obtained. Similarly, using P2 as the starting point, a linear equation of the line segment P2Qi 'is obtained, and the intersection point of the line segment P1Qi and the line segment P2Qi' is set to P
It is set to 0 '(ST10).

After transmitting the coordinate data (ST1
1) Return to step 2. If it is not the first welding in step 7, the coordinate data is immediately transmitted (ST11).

Further, the image pickup device 13 picks up the molten pool image together with the light section image. When the welding voltage is reduced and the arc light is reduced, the high-speed shutter is used to increase the intensity of the pulse laser light, and the arc light and the weld pool image are relatively reduced, and the relative laser light is used. Since the light section image and the molten pool image are captured through the interference filter 14 that increases the intensity, the shape of the molten pool can be clearly captured.

After the imaged molten pool image is binarized by the image processing device 15, the center of gravity of the image is detected as shown in FIG. By adding an initial setting value at the center of gravity, the wire tip position, which is an arc point, is calculated, and a desired coordinate value is obtained by three-dimensional coordinate conversion.

Here, the initial setting value added to the arc light image will be described. As shown in FIG. 17A, the coordinates on the camera image of the tip of the wire that contacts the front and back of the groove at the welding start point are (Xa, Ya), (Xb, Yb), respectively.
Also, as shown in FIG. 17 (b), the center of gravity points of the molten pool image immediately before and after the welding immediately before and after the welding start are respectively (X
a ', Ya'), (Xb ', Yb'), the initial setting values are as follows.

That is, the initial setting value before the groove is DXa = X
a-Xa 'and DYa = Ya-Ya'. On the other hand, the groove back initial setting values are DXb = Xb−Xb ′ and DYb = Yb.
-Yb '.

At this time, as shown in FIG. 18, the image adjustment is performed so that the maximum diameter of the molten pool image is about 50 pixels, so the upper and lower limits of these are as follows.

[Equation 4] In this way, the initial set value is calculated during welding (first weaving) and added after the second weaving to obtain a desired coordinate value.

Then, this calculated coordinate value is compared with the groove feature point coordinates obtained from the light section image, and the deviation is added as a correction value to the torch target position, and based on the result, the welding machine controller 9 Corrects the wire tip position of welding torch 3.

Specifically, the welding machine control device 9 changes the torch aiming position and the swing width on the front side and the back side of the groove on the basis of the calculated groove feature point coordinates. At this time, as shown in FIG. 7A, the wire tip position coordinates are compared with the groove front P2 point or the groove back P0 point, respectively, and if there is a deviation, the difference is used as a correction value for the welding torch 3 Control. Further, the weaving pitch is changed to reflect the change in the laminated thickness in the next layer welding.

Further, based on the molten pool image shown in FIG. 16, the image processing device 15 calculates the coordinate difference between the center of gravity and the center point of the molten pool image. Deformation of the shape of the molten pool can be known from this calculated value, and fine welding condition control can be performed by calculating the penetration depth from the area and width of the molten pool.

Specifically, the center point in each of the X and Y directions is calculated from the minimum X and Y coordinates and the maximum X and Y coordinates of the molten pool image shown in FIG. That is, X of the center point of the molten pool image,
If the minimum X coordinate is X0, the maximum X coordinate is X1, the minimum Y coordinate is Y0, and the maximum Y coordinate is Y1, the Y coordinate is ((X
0 + X1) / 2 and (Y0 + Y1) / 2) are calculated.

The center point coordinates ((X0 + X1)
/ 2, (Y0 + Y1) / 2) and the coordinates of the center of gravity are compared to identify the molten pool shape abnormality and record it as online welding process monitoring data. Further, the welding condition control can be performed by measuring the molten pool area A and comparing it with preset table data to estimate the penetration depth.

Further, when the ratio of the average values of the welding currents before and after the groove exceeds a predetermined value, it is determined that the wire tip position is inside the groove. Specifically, the average value and standard deviation of the welding current and voltage when moving from the front of the groove to the back of the groove are taken, and if the standard deviation is within a certain set value, the average value is recorded.

Next, the average value and standard deviation of the welding current and voltage at the back of the groove are taken, and when the standard deviation is within a certain set value, the recorded average value and the average value at the back of the groove are compared. If the ratio is within a certain set value, it is determined that the wire tip position is behind the groove.

[0100] Specifically, the front side A to the groove shown in FIG.
The average value Ia of the welding current at the position A'is represented by the following mathematical formula.

(Equation 5) In addition, the average value Ib of the welding currents at the groove depths BB ′ shown in FIG. 19 is represented by the following mathematical formula.

(Equation 6) K (K = Ib / I), which is the ratio of these actual values (average values)
When a) is 0.9 times or more of the set value k (k = ib / ia, ia: groove front current set value, ib: groove back current set value), the wire tip position is in the groove back. To determine.

When the wire tip position is determined, the wire tip position of the welding torch 3 is corrected as follows. That is, when it is determined that the wire tip position is not at the groove depth, a preset correction value is added to the initial setting value for calculating the wire tip coordinate point from the weld pool image center of gravity, and this is added to the next wire. By using it for calculating the tip position, extremely precise copy welding can be performed.

As described above, the copy welding method of this embodiment is
When the welding voltage decreases and the arc light decreases, the irradiation of the laser linear light of the high-power pulsed laser and the opening of the high-speed electronic shutter are synchronized to increase the intensity of the laser linear light and to generate an intense arc. Light and molten pool are reduced relatively. Therefore, since the light section image and the molten pool image can be captured and imaged in the same visual field of one image pickup device 13, unlike the above-described reference example 2, the optical axis alignment of the optical system can be easily performed. You can

Further, by extracting the coordinates of the groove characteristic points from the light section image and calculating the wire tip position from the molten pool image, it is possible to cope with thermal deformation of the groove, bending of the wire tip, etc. Welding can be performed.

Further, by grasping the deformation of the shape of the weld pool from the deviation between the center of gravity and the center point of the image of the weld pool, and by calculating the penetration depth from the area and width of the weld pool, fine welding condition control is also possible. Is what you can do.

[0105]

As described above, according to the profiling welding method of the present invention, the arc light and the molten pool radiation light can be relatively reduced with respect to the laser linear light of the high output pulse laser. . Further, even if the laser irradiation portion and the welding portion are brought close to each other in order to cope with thermal deformation of the groove, bending of the wire tip, etc., the influence of arc light and spatter can be completely avoided. Furthermore, by grasping the deformation of the shape of the molten pool from the deviation between the center of gravity and the center point of the image of the molten pool, it is possible to perform fine welding condition control. Therefore, the profile welding method according to the present invention exhibits an excellent effect that extremely precise profile copying can be performed.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the overall structure of a profile welding apparatus used in the profile welding method of the present embodiment.

FIG. 2 is a plan view showing an internal structure of a sensor unit in the copy welding apparatus.

FIG. 3 is a schematic diagram showing a weaving condition and a welding current lowering position in the copying welding method according to the present embodiment.

FIG. 4 is an explanatory diagram showing a relationship between a welding voltage and a set threshold value in the copying welding method according to the present embodiment.

FIG. 5 is an explanatory diagram showing an electronic shutter operating period during weaving in the profile welding method according to the present embodiment.

FIG. 6 is a schematic diagram showing a device block of an electronic shutter actuation by a trigger pulse in the copy welding method of the present embodiment.

7A and 7B show the extraction situation of the feature points in the groove in the profile welding method of the present embodiment, FIG. 7A is an explanatory diagram of the first layer feature points,
(B) is an explanatory view of the characteristic points of the second and subsequent layers.

FIG. 8 is an explanatory diagram showing a flow of extracting groove characteristic points in the profile welding method according to the present embodiment.

FIG. 9 is an explanatory diagram showing the concept of extraction of in-groove feature points in the copying welding method according to the present embodiment.

FIG. 10 shows a search window used for extracting a feature point in a groove in the profile welding method according to the present embodiment.
FIG. 4A is an explanatory diagram of an upward search window, and FIG. 7B is an explanatory diagram of a downward search window.

FIG. 11 is an explanatory diagram showing a shift state of a search window used for extracting a feature point in a groove in the copy welding method according to the present embodiment.

FIG. 12 is an explanatory diagram showing a situation of detection of P1 by a tracking method in extraction of a feature point in a groove adopted in this embodiment.

FIG. 13 is an explanatory diagram showing a P0 detection state by a division / synthesis method in extraction of feature points within a groove used in the present embodiment.

FIG. 14 is an explanatory diagram showing a detection state of P0 by distance calculation in extraction of in-groove feature points adopted in the present embodiment.

FIG. 15 is an explanatory diagram showing the detection status of P0 ′ by the modified tracking method in the extraction of the in-groove feature points adopted in the present embodiment.

FIG. 16 is an explanatory diagram showing a weld pool shape feature amount in the profile welding method according to the present embodiment.

17A and 17B show a calculation state of an initial set value in the detection of the wire tip position adopted in the present embodiment, FIG. 17A is an explanatory diagram of the wire tip position before welding, and FIG. FIG.

FIG. 18 is an explanatory diagram showing the relationship between the maximum diameter of the molten pool and the pixels in the detection of the wire tip position used in this example.

FIG. 19 is a diagram for explaining the range of the average value and standard deviation of the welding current / voltage for determining the groove depth in the detection of the wire tip position adopted in the present embodiment.

[Explanation of Codes] 1 Copy welding device 2 Welding trolley 3 Welding torch 4 Traveling rail 5 Welding arm 6 Forward / backward moving means 7 Up / down moving means 8 Horizontal turning means 9 Welding machine control device (robot controller) 10 Vertical turning means 11 Sensor Unit 12 Laser irradiation device 13 First imaging device 13a Imaging lens 14 Interference filter 15 Image processing device 16 Image capture control device (external trigger controller) 17 Welding power source 18 Camera controller 19 Host computer

Claims (10)

[Claims] 1. When a decrease in welding voltage is detected, a laser beam irradiating device for generating a high-power pulse laser irradiates a groove located in front of the welding torch in the advancing direction with laser linear light, and The high-speed electronic shutter of the image pickup device is opened, the light cut image and the weld pool image are taken through the interference filer, the light cut image is approximated to extract the groove feature point coordinates, and the weld pool image is obtained. The method of profile welding according to claim 1, wherein the wire tip position is calculated by adding an initial setting value to the center of gravity point of, and the wire tip position of the welding torch is corrected based on these values. 2. The profile welding method according to claim 1, wherein the decrease of the welding voltage occurs at the time of transition to the droplet short circuit in the short circuit arc welding. 3. The profile welding method according to claim 1, wherein the decrease of the welding voltage occurs when the power supply current is cut off in pulse arc welding. 4. The high-power pulsed laser is 1-200.
The profile welding method according to claim 1, wherein the output is set to W. 5. The profiling welding method according to claim 1, wherein the laser linear light is applied to a groove located 30 to 100 mm forward of the welding torch in the traveling direction. 6. The copy welding method according to claim 1, wherein the shutter speed of the high-speed electronic shutter is set to 0.1 to 1 msec. 7. The copy welding method according to claim 1, wherein the interference filter is set to have a wavelength of the laser light of ± 10 nm or less. 8. The method according to claim 1, wherein the light section image and the molten pool image are captured a plurality of times, each image is binarized, and the groove feature point coordinates are extracted by a logical product calculation process. The welding method according to any one of 1. 9. The method according to claim 1, wherein the coordinate difference between the center of gravity and the center of the molten pool image is calculated, and the welding condition is controlled based on the calculated value. Copy welding method. 10. The wire of the welding torch is determined based on the fact that the wire tip position is determined to be inside the groove when the ratio of the average values of the welding currents before and after the groove exceeds a predetermined value. The profile welding method according to claim 1, wherein the tip position is corrected.