JPH08276271A - Method and equipment for copy welding - Google Patents

Abstract

PURPOSE: To provide a method and equipment for copy welding capable of completely avoiding the effect of the arc light and the spatter even when a laser beam irradiation part is brought close to a part to be welded, and capable of attaining extremely accurate copy welding. CONSTITUTION: A groove located immediately close a head of a welding torch 3 in the advancing direction is irradiated with the laser beam, and when the droplet short circuit transfer state obtained, a liquid crystal shutter 13 of a photographing equipment 14 provided with an interference filter 15 is opened to photograph the light cutting image, and then, the liquid crystal shutter 13 is closed to photograph the arc light image, and the copy welding is achieved based on the light cutting image and the arc light image.

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 and apparatus.

[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. 62-330.
Invention relating to the "automatic multi-layer welding device" disclosed in Japanese Patent Laid-Open No. 64 (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 cited example 1, "an image pickup device for picking up an image of a molten pool, an arc and its front side, a slit light for obliquely projecting a slit light to a filter group and a base material provided in front of this image pickup device. A sensor system consisting of a projector, an image processing system that captures and stores the shape of the projected slit light and reads the shape characteristics of the molten pool, and is connected to this image processing system to calculate the read groove shape characteristic values. And a controlled system that controls the copying and welding conditions by comparing the groove shape characteristic values with the arc and molten pool characteristic values. "

That is, in the cited example 1, the powerful radiant light from the arc / molten pool is removed by opening / closing the electric filter in synchronization with the timing signal of the arithmetic unit when the groove shape information is taken in by the slit light. At the same time, the problem of practical space and control time delay is avoided, and arc,
It is possible to control the welding conditions in real time by detecting the state of the molten pool and the groove shape.

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]

In the cited examples 1 and 2, the arc light is blocked by the filter, but it is still difficult to completely remove the influence. Also, when performing image processing, it is 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 part and the welding part to some extent, but on the other hand, when the distance between them increases, thermal deformation of the groove and the tip of the wire. 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 completely eliminate the influence of arc light and spatter 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 and bending of the wire tip. It is an object of the present invention to provide a profile welding method and a profile welding apparatus used for the profile welding method, which can be avoided and can perform extremely precise welding profile.

[0011]

In order to achieve the above object,
The copy welding method according to the present invention is performed during 1 pass 1 rare welding,
When the laser linear light is radiated to the groove located immediately in front of the direction of travel of the welding torch, the welding current is reduced and the liquid crystal shutter provided in the imaging device is opened when the droplet short-circuiting state is reached. A light cut image is taken through an interference filter, the liquid crystal shutter of the image pickup device is closed to take an arc light image in front of and behind the groove, and the light cut image is approximated and opened. Along with extracting the coordinates of the previous feature point, adding the initial setting value to the center of gravity of the arc light image to calculate the wire tip position of the welding torch, and correcting the wire tip position of the welding torch based on these Is.

In the configuration of the above-mentioned profile welding method, preferably, the laser linear light is applied to the groove located 30 to 100 mm forward of the welding torch in the traveling direction.

Further, preferably, the welding current in the droplet short-circuit transfer state is set to 200 A or less at the front position of the groove.

Further, preferably, the interference filter is set to have a wavelength of the laser beam of ± 20 nm or less.

Preferably, in the droplet short-circuit transition state, the light-section images are imaged a plurality of times during the short-circuit transition, the light-section images are binarized, and the groove characteristic is calculated by a logical product calculation process. The point coordinates are extracted.

In addition, preferably, when the ratio of the average values of the welding currents in front of the groove and behind the groove exceeds a predetermined value, it is determined that the tip position of the wire is inside the groove, and based on this. The position of the wire tip of the welding torch is corrected.

On the other hand, the profile welding apparatus according to the present invention has a welding torch mounted on a welding carriage that travels along a joint groove and a front 30 to 100 in the traveling direction of the welding torch.
The laser irradiation device that irradiates the laser linear light perpendicularly to the groove located at mm, and the liquid crystal shutter is opened to capture a light cut image of the laser linear light. An image pickup apparatus for picking up an optical image, and image processing for calculating the wire tip position by adding the initial setting value to the barycentric point of the arc light image while extracting the groove feature point coordinates from the light cut image by approximation processing. An apparatus and a welding machine controller that controls the welding torch based on the calculated value of the image processing apparatus and corrects the wire tip position.

In the configuration of the above-mentioned copy welding apparatus, it is preferable that the image pickup apparatus has a wavelength of the laser beam of ± 20 nm.
The following interference filters are provided.

Preferably, the image pickup device is a CC
It is formed by a D camera.

Further, preferably, the image processing apparatus is provided with an image capturing control device which transmits a trigger pulse to instruct image capturing when the welding voltage falls below a set threshold value.

[0021]

According to the configuration of the above-described profile welding method, the laser linear light is applied to the groove located immediately in front of the welding torch in the traveling direction. 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, the imaging is provided with an interference filter for increasing the relative intensity of the laser light when the arc current is reduced by reducing the welding current to bring the droplet into a short circuit state. Since the device takes a light section image, the influence of arc light can be completely avoided. At that time, the liquid crystal filter provided in the image pickup device is opened.

Further, the liquid crystal filter is closed by the same image pickup device to pick up an arc light image of the welding torch before and after the groove. In this way, by closing the liquid crystal filter only when capturing an arc light image, intense arc light can be captured in a dot shape.

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 captured, and the arc is set by adding the initial setting value to the center of gravity of the arc light image. The wire tip position, which is a point, is calculated, and this calculated value is compared with the groove feature point coordinates obtained from the above optical cutting image, and if the deviation is added as a correction value to the torch target position, a precise welding profile is obtained. Is what you can do.

In particular, when the laser linear light is applied to the 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. .

The reason why the welding current in the droplet short-circuit transition state is set to 200 A or less is that the arc light is reduced during the droplet short-circuit transition in order to avoid the influence of intense arc light. is there. And welding current is 200A
The reason why the groove front position is set below is that the welding quality is relatively unaffected.

Further, the reason why the interference filter is set to a wavelength of the laser beam of ± 20 nm or less is that the wavelength of the semiconductor laser has a variation of about ± 20, and therefore the filter needs to have a similar half width.

Then, in the above droplet short circuit transition state,
The light section image is taken during the short circuit transition because the arc is momentarily cut off during the short circuit transition. In addition, the light section images are taken multiple times during the transition to the short circuit, the light section images are binarized, and the groove feature point coordinates are extracted by the AND operation process. This is because a large number of noise image components such as spatters are included, and thus the logical product arithmetic processing is performed between the binarized images of a plurality of surfaces to remove these noises appearing at unspecified locations.

Further, when the ratio of the average value 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 of the welding current when moving from the front of the groove to the back is taken and recorded. Next, take the average value of the welding current at the back of the groove, compare the recorded average value before the groove with the average value at the back of the groove, and if the ratio is within a certain set value It is determined that the wire tip position is located behind the groove. Based on this judgment,
Precise welding copying will be performed.

On the other hand, according to the configuration of the copy welding apparatus,
When the welding carriage moves and moves, the welding torch mounted on the carriage moves along the joint groove. The laser irradiation device irradiates a laser beam linearly to a groove located 30 to 100 mm forward of the welding torch in the traveling direction. Next, the image pickup device picks up an optical cutting image of the laser linear light and an arc light image from diagonally forward of the welding torch. When the light cutting image is taken, the liquid crystal shutter is opened and the arc light image is picked up. When doing, the liquid crystal shutter is closed.

Further, the image processing apparatus extracts the groove feature point coordinates by the approximation process, that is, the linear approximation and / or the curve approximation, from the picked-up light-section image, and initializes the barycentric point of the arc light image. The wire tip position is calculated by adding the calculated value, and the calculated value is compared with the groove feature point coordinates extracted from the light section image, and the deviation is added as a correction value to the torch target position. Then, the welding machine control device controls the welding torch based on the calculated value of the image processing device, and corrects the wire tip position.

In particular, the image pickup device is provided with an interference filter having a wavelength of the laser beam of ± 20 nm or less.
Since the imaging device captures the light-section image of the laser linear light through the interference filter, the relative intensity of the laser light increases, and the light-section image can be captured clearly. Further, since this image pickup device is provided with a liquid crystal shutter, the light cut image and the arc light image can be taken by the same image pickup device by opening and closing the liquid crystal shutter appropriately.

Further, if the image pickup device is formed by a CCD camera, it is smaller and easier to handle than a pickup tube camera, and problems such as burning can be eliminated.

Since the image capture controller sends a trigger pulse to instruct image capture when the welding voltage drops below the set threshold, the threshold is set so that the trigger pulse is synchronized with the transition to the short circuit. If set, a light section image can be taken at the moment when the arc is cut.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the method and apparatus for profile welding according to the present invention will be described in detail below 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 of the present embodiment 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 disposed 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 back-and-forth 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.

The welding carriage 2 is also equipped with a sensor unit 11 shown in FIG. 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 linear laser beam toward the joint groove and an imaging device 14 including a liquid crystal shutter 13 are housed.

The laser irradiation device 12 has a wavelength of 680 ± 10.
nm, a 35 mW output semiconductor laser, and a collimating lens for linearizing the laser beam,
Cylindrical lenses 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 image pickup device 14 is configured to open the liquid crystal shutter 13 to pick up a light cut image of laser linear light, and to close the liquid crystal shutter 13 to pick up an arc light image. Further, the image pickup device 14 employs a CCD camera capable of opening the electronic shutter within a set time after a delay of about 1 μS with respect to a trigger signal from the outside. That is, the electronic shutter opens and closes when capturing an image, and the liquid crystal shutter 13 opens and closes for the purpose of selecting an image capturing target.

As shown in FIG. 3, the liquid crystal shutter 13 opens and closes the liquid crystal portion 13b located on the optical axis when an electric signal is input from the input terminal 13a. It is a device in which the transmittance increases and the transmittance of the liquid crystal part 13b decreases when the liquid crystal part 13b is closed, and is mounted in front of the imaging lens 14a of the imaging device 14. In this embodiment, for example, VS2200 (manufactured by Nippon Kogaku Co., Ltd.) is adopted.

Further, the CCD camera is adopted as the image pickup device 14 because the CCD camera has advantages that it is smaller and easier to handle than an image pickup tube camera, and there is no problem such as burning, and that the two-dimensional CCD is used. Compared to the one-dimensional type, when using an element, mechanical laser scanning is unnecessary, so there are few failures, and two-dimensional information is handled, making it easy to perform image processing such as shape recognition. This is because there is an advantage that

Further, the image pickup lens 1 of the image pickup device 14
An interference filter 15 having a wavelength of laser light (680 nm) ± 10 nm is provided in front of 4a and the liquid crystal shutter 13. The wavelength of the interference filter 15 is set to the laser wavelength ± 10 nm because the interference filter is used to increase the relative intensity of the laser light, but the wavelength of the semiconductor laser has a fluctuation of about ± 10 nm. This is because the interference filter 15 also needs to have a similar half width.

The image pickup device 14 is connected to an image processing device 16 for arithmetically processing the light-section image of the laser linear light imaged and the arc light image. This image processing device 16
Calculating means for approximating the groove feature point coordinates from the light section image by approximation, that is, linear approximation and / or curve approximation, and adding the initial setting value to the center of gravity of the arc light image to calculate the wire tip position. Is. In addition, the image processing device 16
Is connected to an image capture controller 17 that monitors whether the welding voltage drops below a set threshold value and controls the image capture position.

Further, the image processing device 16 and the image capturing control device 17 are respectively connected to the welding machine control means 9 for controlling the welding torch 3 based on the calculated value of the image processing device 16 and correcting the wire tip position. There is.

Further, the laser irradiation device 12 is set in 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 image pickup device 14 is positioned within the sensor unit 11 so as to pick up the light section image and the arc light image from diagonally forward of the welding torch 3, respectively.

Next, the operation of the above-described profile welding apparatus 1 will be described together with the profile welding method of the present embodiment which is performed by using the profile welding apparatus 1. When welding the groove of blast furnace iron skin, 1 pass, 1 rare,
Welding is performed using the horizontal welding method with a change in the torch angle. At this time, the profile welding apparatus 1 causes the welding carriage 2 to travel along the traveling rail 4, and the welding machine control device 9 causes the forward / backward moving unit 6, the vertical moving unit 7, the horizontal rotating unit 8, and the vertical rotating unit 10 to move. The automatic torch welding is performed by weaving the welding torch 3 by controlling four axes.

In the profile welding method of this embodiment, first, a laser linear light is irradiated from the laser irradiation device 12 housed in the sensor unit 11 to a groove located in front of the welding torch 3 in the traveling direction. .

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.
The laser linear light is radiated perpendicularly to the groove at a position separated by about mm. The irradiation position of the laser linear light is set 30 to 100 mm forward of the traveling direction of the welding torch 3 is 30 m.
This is because if it is less than m, the influence of the arc light is too strong,
This is because if it exceeds 100 mm, it becomes difficult to cope with the shape deformation due to welding heat in the case of a groove having an extremely thick plate such as a blast furnace iron skin.

Next, the welding current is reduced to reduce the welding torch 3.
The welding wire fed out from is brought into a droplet short-circuit transfer state. Specifically, the welding current is reduced to 200 A or less at the position before the groove to bring the welding wire into a droplet short circuit transition state. The reason why the welding current is set to 200 A or less is that the arc light is reduced at the time of transition to the droplet short circuit in order to avoid the influence of the intense arc light.

That is, in the case of the MAG welding used in this embodiment, 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. 4, by dropping the welding current at a position where the weaving locus W is at the groove front portions A to B (A is a welding current decrease start point, B is a welding current decrease end point), the welding current is 200 A or less, It is possible to measure. The reason why the welding current is lowered 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, when the welding voltage is monitored by the image capturing controller 17, and when it falls below the set threshold value, the liquid crystal shutter 13 and the electronic shutter of the imaging device 14 are opened. A light cut image of the laser linear light is taken through the interference filter 15. When the liquid crystal shutter 13 is opened, the transmissivity of the liquid crystal portion 13b located on the optical axis increases, so that a light-section image can be easily captured. The wavelength of the interference filter 15 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 14
The light section image picked up in is input to the image processing device 16.

That is, as shown in FIG. 5, assuming that the groove front voltage setting value is Va and the threshold value is 0.6 Va, a trigger pulse is generated in synchronization with the falling edge of the signal that results in 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 electronic shutter 4 will be opened within the set time. In synchronization with this, the liquid crystal shutter 13 is also opened, and the transmittance of the liquid crystal portion 13b increases.

More specifically, as shown in FIG. 6, the short circuit period is in the front part of the groove where the welding current is reduced, but the period when the image pickup device 14 is stopped in the welding direction can be captured. (Enable).

Then, as shown in FIG. 7, the welding power source 1 is controlled by the image capture controller (external trigger controller) 17.
The welding voltage V of No. 8 is monitored, and the welding voltage V is 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.9. R. When an input (reset / restart) is entered, the electronic random shutter is released, an interrupt is generated in the host computer 20 at the same time, and if it is an enable period, the image processing device 16 is instructed to capture an image. The welding power source 18 is connected to the host computer 20 via the welding machine control device (robot controller) 9.
Connected with.

Since image measurement by the interference filter 15, the liquid crystal shutter 13 and the electronic shutter alone is not sufficient for image measurement, the image quality is improved by image processing. That is, in the droplet short-circuit transition state, the light-section image is captured twice by the imaging device 14 during the short-circuit transition. The light-section image is captured twice because the light-section image of the laser linear light during welding contains many noise image components such as spatter in the image, so that the binarization processing (black and white This is to remove these noises appearing at unspecified locations by performing a logical product operation process between the processed images.

Specifically, in FIG. 4, the light section image (shown in FIG. 8A) taken at the position A'is recorded in the image memory and the moment A'followed by the short circuit A is recorded. The light section image of '' (shown in FIG. 8B) is taken in, binarization processing and smoothing processing are performed together with the recorded image, and then the logical product (AND) processing for each pixel between the two images. And remove the noise image (shown in FIG. 8C). If necessary, the same logical product operation is performed on the next image.

Next, for the ANDed 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. 8D, and the desired coordinate values are obtained by three-dimensional coordinate conversion. 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.

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) is 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. 10, 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 1 (a), Pe
From here, the upward search window shown in FIG. 11 (b) is used.

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.

If the connection is interrupted, 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, a 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 center of Qi + 1 and a radius of r. 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. 14, 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]

Further, as shown in FIG. 15, 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. 16, 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 with a 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 expression 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).

The image pickup device 14 includes a liquid crystal shutter 13
Closed to capture an arc light image in front of and behind the groove. When the liquid crystal shutter 13 is closed, the transmittance of the liquid crystal portion 13b located on the optical axis decreases, so that the arc light brightness can be reduced and intense arc light can be captured as a dot image. Specifically, as shown in FIG.
When the weaving locus is located at the groove front portion B ′ and the groove depth C, the liquid crystal shutter 13 is closed and the electronic shutter is opened, so that the imaging device 14 captures an arc light image. Are taken into the image processing device 16.

The image processing device 17 binarizes the point-shaped arc light image picked up by the image pickup device 14 and then detects the center of gravity thereof. 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.
In addition, as shown in FIG. 17 (b), the center of gravity points of the arc light image before and after the groove immediately after the start of welding 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, image adjustment is performed so that the maximum diameter of the arc light image is about 50 pixels. Therefore, 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, the calculated coordinate values are 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 online based on the calculated groove feature point coordinates. At this time, as shown in FIG. 8D, the wire tip position coordinate is 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, when the ratio of the average value 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 of the welding current when moving from the front of the groove to the back of the groove is taken and recorded.

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

Specifically, before the groove A 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 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 center of gravity of the arc image, and this is added to the next wire tip. By using it for calculating the position, extremely precise copy welding can be performed.

As described above, according to the present embodiment, by opening and closing the liquid crystal shutter 13 of the single image pickup device 14, it is possible to pick up the light section image and the arc light image within the same visual field with a time difference. It is possible, by extracting the groove feature point coordinates from the light cut image and calculating the wire tip position from the arc light image, it is possible to respond to the shape deformation of the groove and the bending of the wire tip due to welding heat, It is possible to perform extremely precise welding copying.

As a comparative example of this example, the above-mentioned reference example 2 can be cited. However, the second reference example has a complicated structure and it is difficult to align the optical axis, and the applicable groove shape is also limited. In addition, in order to avoid the effect of intense arc light, the laser linear light must be far away from the welding point, and because it is difficult to detect the wire tip position accurately, thermal deformation of the groove or wire It cannot deal with bends and the like.

[0097]

As described above, according to the copy welding method and apparatus according to the present invention, the laser irradiation portion and the welding portion are made to correspond to the shape deformation of the groove and the bending of the wire tip due to welding heat. Even if they are brought close to each other, the effect of arc light and spatter can be completely avoided, and an excellent effect that extremely precise welding copying can be performed is exhibited.

[Brief description of drawings]

FIG. 1 is a schematic view showing the overall structure of a copy welding apparatus according to this embodiment.

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

FIG. 3 is a schematic view showing a liquid crystal shutter in the copy welding apparatus according to the present embodiment.

FIG. 4 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. 5 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. 6 is an explanatory diagram showing an electronic shutter operation period during weaving in the profile welding method according to the present embodiment.

FIG. 7 is a schematic diagram showing a device block of electronic shutter actuation by a trigger pulse in the copying welding method of the present embodiment.

8A and 8B show extraction conditions of groove feature points in the profile welding method according to the present embodiment, FIG. 8A is an explanatory view of a light section image at A ′, and FIG. 8B is a light section image at A ″. Illustration,
(C) is an explanatory view of an image after a logical product operation, (d) is an explanatory view of first-layer feature points, and (e) is an explanatory view of second-layer and subsequent feature points.

FIG. 9 is an explanatory diagram showing a flow of extracting groove characteristic points in the profile welding method according to the present embodiment.

FIG. 10 is an explanatory diagram showing the concept of extraction of in-groove feature points in the profile welding method of the present embodiment.

FIG. 11 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. 12 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. 13 is an explanatory diagram showing the detection status of P1 by the tracking method in the extraction of the in-groove feature points used in this embodiment.

FIG. 14 is an explanatory diagram showing a P0 detection state by a division / synthesis method in extraction of feature points within a groove used in this embodiment.

FIG. 15 is an explanatory diagram showing a detection state of P0 by distance calculation in extraction of a feature point in a groove adopted in the present embodiment.

FIG. 16 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.

17A and 17B show a calculation situation of an initial setting value in the detection of the wire tip position adopted in the present embodiment, FIG. 17A is an explanatory view 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 arc light and the pixel in the detection of the wire tip position adopted in this embodiment.

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 symbols]

DESCRIPTION OF SYMBOLS 1 Copy welding apparatus 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 Liquid Crystal Shutter 13a Input Terminal 13b Liquid Crystal Section 14 Imaging Device 14a Imaging Lens 15 Interference Filter 16 Image Processing Device 17 Image Capture Control Device (External Trigger Controller) 18 Welding Power Supply 19 Camera Controller 20 Host Computer

Claims (10)

[Claims] 1. During 1-pass 1-rare welding, when a linear laser beam is radiated to a groove located immediately in front of the direction of travel of a welding torch, the welding current is reduced and a droplet short-circuiting transition state occurs. ,
The liquid crystal shutter provided in the image pickup device is opened, the light cut image is taken through the interference filter, and the liquid crystal shutter of the image pickup device is closed to take the arc light image before and after the groove. Then, while approximating the light cut image to extract the groove feature point coordinates, add the initial setting value to the center of gravity of the arc light image to calculate the wire tip position of the welding torch, and based on these, welding A profiling welding method characterized in that the position of the tip of the wire of the torch is corrected. 2. 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. 3. The copy welding method according to claim 1, wherein the welding current in the droplet short circuit transition state is set to 200 A or less at the front position of the groove. 4. The copy welding method according to claim 1, wherein the interference filter is set to have a wavelength of the laser light of ± 20 nm or less. 5. In the droplet short-circuit transfer state, the light-section images are imaged a plurality of times during the short-circuit transfer, these light-section images are binarized, and the groove feature point coordinates are calculated by a logical product calculation process. The profile welding method according to any one of claims 1 to 4, which is adapted to be extracted. 6. 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. 7. A welding torch mounted on a welding carriage that travels along a joint groove, and a laser linear light is perpendicular to the groove located 30 to 100 mm forward of the welding torch in the traveling direction. A laser irradiation device for irradiating, an imaging device for opening a liquid crystal shutter to capture a light cut image of laser linear light, and closing a liquid crystal shutter for capturing an arc light image; An image processing device that calculates the wire tip position by adding the initial setting value to the barycentric point of the image of the arc light as well as extracting the characteristic point coordinates by approximation processing, and a welding torch based on the calculated value of the image processing device. A profile welding apparatus, comprising: a welding machine control device that controls and corrects a wire tip position. 8. The wavelength of the laser light
8. An interference filter of 20 nm or less is provided.
The copying welding device described in. 9. The profile welding apparatus according to claim 7, wherein the imaging device is formed by a CCD camera. 10. The image processing apparatus according to claim 7, further comprising an image capturing control device which transmits a trigger pulse to instruct image capturing when the welding voltage is lower than a set threshold value. The copy welding apparatus according to any one of 1.