JPH0234280A - Method and device for photographing arc welding - Google Patents

Abstract

PURPOSE:To improve welding control accuracy by providing a switching element capable of synchronizing externally and a telecamera wherein a shutter is incorporated and executing shutter opening and shutting operation during interrupting of a power source current for the specific time. CONSTITUTION:The telecamera 2 wherein the shutter is incorporated capable of synchronizing externally is connected to a synchronizing signal generating device 1 and the switching element 5 to interrupt the welding power source current in synchronization with a signal is arranged. The camera 2 with the shutter and a welding torch are fitted to a traveling carriage and welding is performed while monitoring a monitoring television 4. At this time, the interrupting time of the welding power source current is regulated to 1/2000-1/10 sec and interrupting is repeated and during that time, the switching element 5 is synchronized with the camera 2 to execute shutter opening and shutting. Since an arc 9, a pool 7, a bead 8, a groove 6, etc., can be observed under a proper photographing condition, welding control accuracy at the time of welding work is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an arc welding photographing method and apparatus that monitor arc welding and control welding by image processing.

[Conventional technology]

In normal arc welding, the welder uses an arc 9. The welding condition is determined while observing the pool 7, bead 8, and groove 6, and the welding control operation end is operated accordingly to perform proper welding. However, in dangerous welding areas or narrow welding areas where the welder cannot directly observe or operate, the welding condition may be photographed with a television camera 12, observed on a monitor television 4, and controlled remotely, or the video signal may be image-processed. A method of automatically controlling a welding machine using this has been attempted.

In order to remotely control or automatically control arc welding using this method, the arc, pool, bead, and groove must be well photographed.

However, there are problems with photographing arc welding using a television camera.

Figure 8 shows the incident light and light intensity range a when a filter or a squeezer is not used on a TV camera during arc welding, and the incident light and light intensity range A and C1 when a filter or a squeezer is used, and the TV camera. As shown in FIG. 8a, the incident light of the television camera during arc welding, that is, the arc, pool,
The light intensity range constituting the bead and groove images is much wider than the appropriate sensitivity range of a television camera. This is because the arc light emits a strong light and is very bright.

This is because the bead and groove are darker than the arc.

Therefore, if the filter is darkened or the aperture is closed in order to properly photograph arcs with strong light intensity, the areas with weak light intensity will be below the lower sensitivity limit of the image sensor, as shown in Figure 8b, resulting in pools, beads, etc. The groove cannot be imaged.

In addition, if the filter is thinned or narrowed down to take good pictures of pools, beads, and grooves, the areas with strong light intensity will exceed the upper limit of sensitivity of the image sensor, as shown in C in Figure 8, so the arc area cannot take pictures.

Several photographic methods have been tried in the past to solve these problems, but the main method is
This method is described in Japanese Patent No. 1-71182 and utilizes the difference in wavelength between the light spectra of arc light and pool radiation light to synthesize images taken with filters having different characteristics to obtain a good image.

FIG. 9 shows an example of the optical spectrum intensity of arc light and pool radiation light. As shown, arc light has a short wavelength and pool radiation light has a long wavelength. Therefore, arcs and pools can be observed well by processing and combining a pool image taken with a filter that blocks short wavelength light and an arc image that has been dimmed and blocked long wavelength light.

[Problem to be solved by the invention]

However, as shown in Figure 9, arc light has strong light intensity over a wide wavelength range, so it is not possible to sufficiently attenuate arc light by simply using a filter that attenuates short wavelength light; If a light attenuation filter is used, the pool image will also be attenuated.

Therefore, filter selection alone is not sufficient for arc, pool,
It was difficult to properly image the grooves and beads.

The present invention aims to solve the above-mentioned problems using an arc welding photographing method and apparatus that are completely different from the conventional techniques, and to provide a method and apparatus that can photograph arcs, pools, beads, and grooves well. .

[Means to solve the problem]

The gist of the present invention is to reduce the current from the welding power source by 1/2000 to
An arc welding photographing method characterized by repeatedly performing a 1/10 second interruption operation and opening and closing the shutter of a television camera during the current interruption time in synchronization with the above time, and a synchronization signal generator and the synchronization. Arc welding characterized by comprising an externally synchronizable switching element that interrupts the current of a welding power source by a signal from a signal generator, and a television camera incorporating an externally synchronizable shutter that opens and closes in synchronization with the above time. This is a photographic device that can take good pictures of the arc, pool, bead, groove, and wire tip during arc welding.

[For production]

The arc welding photographing method of the present invention is a method in which the welding current is cut off for a short period of time, and the arc, pool, bead, and groove are properly photographed by photographing while the arc light is attenuated.

However, if the welding amount circle is interrupted for a long time, good photography can be obtained, but it is difficult to re-arc, and the arc becomes unstable, making it more likely that defects will occur.

Also, if the time to cut off the welding critical point is short, the arc light will not be dimmed sufficiently, making it impossible to take good photographs.
The following experiment was conducted in order to find an appropriate welding electrician cut-off time.

The device uses a synchronizing signal generator l as shown in FIG.
The shutter-equipped television camera 2 and the switching element 5 were controlled so that the shutter open time T was set and photographed in a region where the arc light intensity was low after the welding current cut-off time Tc, as shown in FIG. In addition, at this time, a television image recording device 3 is arranged as shown in FIG. 1 so that it can be easily observed on a monitor television 4, and the image signal of the television camera 2 with a shutter that is sporadically output is recorded. Between the shootings, the recorded image signals were repeatedly output to the monitor television 4 as shown in FIG. The switching element 5 uses a transistor and can be turned on and off in response to a synchronizing signal.
The shooting was carried out at a constant rate of 1 second, and the shooting was repeated once every second.

Welding was carried out under the conditions shown in Table 1, with the plate thickness It = shown in Figure 4.
30 mm, groove angle θ・40°, root width G=6 mm
.

Welding was performed inside the groove with a groove depth D=15 mm+. Welds are evaluated using an X-ray transmission test (JIS Z 3104), with grade 1 being good and grade 2 or lower being poor, and arcs, pools, beads, and grooves that can be clearly observed in a photographic test being good, and those that are difficult to observe. If both the X-ray transmission test evaluation and the photographic test evaluation were good, the overall evaluation was good, and if not, the overall evaluation was bad.

The experimental results are shown in Table 2. From Table 2, if the welding current interruption time is 1710 seconds or less, the arc is stable and the X-ray transmission test is good, and if the welding current interruption time is 1/2000 seconds or more, the photographic test is good, and the welding current interruption time is 1/2000 seconds or more. 2000～
It was found that a range of 1/10 seconds was good.

O: Good ×: Bad [Example] Next, the method of the present invention and the conventional method will be explained based on an example in which welding was performed by remote control using an arc welding monitor device.

In the method of the present invention, the television camera 2 with a shutter shown in FIG.
The welding torch 13 was attached to the traveling cart 15 shown in the figure, and the welding torch 13 was attached to a remotely controllable welding torch left/right setting machine 14, and welding was performed while watching the monitor television 4 and adjusting the welding torch 13 left and right.

In the conventional method, as shown in FIG. 3, a shutterless television camera 12 equipped with a filter 16 that attenuates short wavelength light of about 900 μm or less used to attenuate welding arc light is mounted on a traveling trolley 15 as shown in FIG. Similar to the method of the present invention, the welding torch 13 was adjusted from side to side while watching the monitor television 4, and welding was performed.

Welding was performed using the wire, steel plate, and welding conditions shown in Table 1.
As shown in Figure 6, the groove is 11.30mm thick and the width is -=
Bevel angle θ・4 on steel plate with 500 cylinder and plate length LJOOOOmm
0°, groove depth D-15am, root width G-6m, both ends ^, point C and the distance S 50■ in the board width direction. Grooves were machined.

The evaluation method was to input the output of the botensio installed in the traveling carriage 15 and the welding torch left/right setting machine 14 into an XY recorder, and record the movement trajectory 18 shown in FIG. 7 of the welding torch 13 during welding. In addition, before welding, welds were connected in straight lines at the groove center points A, B, and C shown in FIG. 6, and a groove center line 17 shown in FIG. 7 was drawn. This movement trajectory 18
If the deviation of the groove center line 17 is 1- or less, it is good.
If it exceeded ll11, it was evaluated as poor.

Table 3 shows the implementation results. From Table 3, the method of the present invention allows for good observation of arcs, pools, beads, and grooves, making it easy to finely manipulate the groove during welding. The deviation of the movement trajectory 18 was 0.6 mm at most, and the evaluation was good. However, with the conventional method, it is difficult to observe the groove, pool, arc, and wire tip, making it difficult to finely manipulate the groove during welding. The evaluation was poor.

Table 3 [Effects of the Invention] As described above, the arc welding photographing method and device of the present invention allows the arc, pool, groove, bead, and wire tip of arc welding to be observed well with a television camera, so that Monitoring and remote control are easy and can greatly contribute to labor savings in monopolized work.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the arc welding photographing method of the present invention, Fig. 2 is a diagram showing an example of a timing chart 1 for synchronizing a switching element, a television camera with a shack, and a television image recording device, and Fig. 3 is a conventional diagram. Figure 4 is a cross-sectional view showing the groove shape used in the basic experiment, Figure 5 is an installation diagram of the traveling trolley, camera, and welding torch used in the example, Figure 6 7 is a diagram showing the groove shape used in the example, FIG. 7 is a diagram showing an example of a record of the movement trajectory of the welding torch and the groove center line recorded on the XY recorder, and FIG. 8 is a diagram of the arc light beam in arc welding. Figure 9 is a schematic diagram showing the light intensity range when transmitted through a filter, and the sensitivity range of the image sensor.
FIG. 3 is a diagram showing an example of the optical spectral intensity distribution of the curved light and the groove light. ■... Synchronization signal generator, 2... Television camera with shutter, 3... Television image recording device, 4... Monitor television, 5... Switching element, 6... Bevel, 7
...pool, 8...bead, 9...arc, IO
... wire, 11 ... welding power source, 12 ... shutterless television camera, 13 ... welding torch, 14 ...
・Welding torch left and right setting machine, 15... Traveling trolley, 16.
... Filter, 17... Groove center line, 18... Movement trajectory. π1 figure agent Patent attorney Masamitsu Akizawa and 1 other figure 2 figure 4 figure piece 5 figure Muka aJ48 ('@', sir 7i6 figure 3 figure O8 figure 7q figure board length (μt)

Claims (2)

[Claims] (1) It is characterized by repeatedly performing the operation of cutting off the current from the welding power source for 1/2000 to 1/10 seconds, and opening and closing the TV camera jack during the current cutoff time in synchronization with the above time. Arc welding photography method. (2) A television camera that incorporates a synchronization signal generator, an externally synchronizable switching element that cuts off the current of the welding power source by the signal from the synchronization signal generator, and an externally synchronizable shutter that opens and closes in synchronization with the above time. An arc welding photographing device characterized by comprising: