JP2002248566A - Method and device for underwater welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To overcome a drawback in a method for conducting mechanical scanning using a single focusing type sensor and to provide a method and device for underwater welding easily observing a welding part thoroughly. SOLUTION: In the underwater welding method, when wet type underwater arc welding is conducted, a plurality of oscillators of an ultrasonic array sensor which are arranged on a welding line are sequentially switched, a welding state is detected by non-contactly and rapidly shifting an ultrasonic beam, and a welding position and welding condition are controlled based on the result. The under water welding device comprises an underwater welding torch 1, an ultrasonic array sensor 9 which is arranged in the forward of a travel direction, an ultrasonic pulsar receiver 17 which transmits and receives an ultrasonic reflection wave, an A/D converter 18 which conducts A/D convert information from the ultrasonic pulsar receiver 17, a computer 19 witch inputs information from the A/D converter 18 and calculates, and a motor driver 20 which operates the underwater welding torch 1 according to output from the computer 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underwater arc welding system for automatically controlling a welding position and welding conditions while observing a state of a welding portion using an ultrasonic sensor in order to automate an underwater welding process. The present invention relates to a method and an apparatus used for the method.

[0002]

2. Description of the Related Art At the time of automatic welding and automatic cutting by a land-based robot, a CCD camera or CCD is used to observe a welding portion, track a welding line, and recognize a welding situation.
A position / shape sensor combining a camera and a laser beam is used. However, in underwater welding, laser light and other light are significantly attenuated in water, and observations are hindered by turbidity and bubbles generated near the work site due to the decomposition of welding slag and fume generated during welding. At present, robots are rarely used, and divers manually select welding conditions while checking the welding conditions manually.

[0003] By the way, ultrasonic waves are much easier to propagate in water than in the atmosphere and are less affected by turbidity of water. Therefore, they are suitable as sensing means for underwater processing technology. Paying attention to this point, when performing wet underwater arc welding first, the welding speed was set to 30 c
m / min or less, and scanning by an ultrasonic sensor in a direction perpendicular to the welding line at a scanning speed of 50 cm / min or more, while observing the welding state of the welding site, and determining the welding position and An underwater welding method characterized by controlling welding conditions was proposed (Japanese Patent Application No. 2001-2001).
39958). However, this method has the disadvantages that it requires a special mechanism for performing mechanical scanning using a single focus sensor, and that scanning is time-consuming.

[0004]

SUMMARY OF THE INVENTION The present invention overcomes the disadvantages of the above-described method of performing mechanical scanning using a single focus sensor, and provides a method of performing underwater welding while simply observing the entire welded area. And a device.

[0005]

The present inventors have conducted various studies on underwater sensing methods using ultrasonic waves in underwater welding. As a result, instead of mechanically scanning a single focus sensor, the present inventors It has been found that the use of a sound wave array sensor enables continuous detection of a welded portion in water, and the present invention has been made based on this finding.

That is, according to the present invention, in performing wet-type underwater arc welding, an ultrasonic beam is rapidly moved in a non-contact manner while sequentially switching a plurality of transducers of an ultrasonic array sensor arranged on a welding line. Underwater welding method, wherein the welding position and the welding conditions are controlled based on the welding condition, and the underwater welding torch 1, an ultrasonic array sensor 9 disposed in front of the underwater welding torch 1, The ultrasonic pulsar / receiver 17 for transmitting and receiving the reflected acoustic wave, and the information from the ultrasonic pulsar / receiver 17
It comprises an A / D converter 18 for D-conversion, a computer 19 for inputting information from the A / D converter 18 and performing arithmetic processing, and a motor driver 20 for operating the underwater welding torch 1 in accordance with an output from the computer 19. An underwater welding device is provided. Here, the ultrasonic array sensor is a sensor that arranges a number of ultrasonic transducers in parallel, moves ultrasonic waves while transmitting and receiving ultrasonic waves at a high speed, and continuously observes an object.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the accompanying drawings. FIG. 1 is an explanatory view showing one example of the method of the present invention. In a submerged welding torch 1, a water curtain 3 ejected in a conical shape from a nozzle outer peripheral portion 2 and carbon dioxide and argon gas filled inside the nozzle are shown. The interaction with the shielding gas 4 eliminates water around the weld, forms a local cavity 5, and creates an arc 8 between the consumable electrode wire 6 and the substrate 7 in the shielding gas 4 in a stable state.
And arc welding is performed. The ultrasonic array sensor 9 is disposed in front of the welding torch 1 in the moving direction, transmits and receives the ultrasonic beam 10, and forms a contour image of a longitudinal section obtained by ultrasonic reflection from the welding bead, a so-called B-scope image. Let it form.

FIG. 2 is a perspective view of an electronic scanning ultrasonic linear array sensor used in the present invention, and FIG. 3 is a plan view of the same. The ultrasonic array sensor itself can be obtained as a commercial product. In these figures, the sensor 9 is constituted by a number of ultrasonic transducers 11,... Arranged in parallel, and by sequentially switching the electronic switch 12 for each transducer at a high speed, the ultrasonic beam 10 is moved in the direction of the arrow. Move linearly. In this way, linear scanning can be performed without moving the sensor itself. At this time, the ultrasonic waveform is generated by the acoustic lens 13 and the matching layer 14.
Is properly shaped by Since each of the transducers 11,... Transmits and receives a few pulses of ultrasonic waves, a thin and sharp image can be formed, and relatively precise measurement can be performed. Information obtained by the measurement is sent to the computer via the transmission / reception circuit 15 and is subjected to predetermined processing.

The width and number of the above-mentioned vibrators differ depending on the object to be monitored, but usually 30 to 200 pieces having a width of 0.5 to 1.5 mm are used in parallel. Also, the sensor 9
The effective field of view is 10 to 7
0 mm, usually in the range of 30 to 50 mm. Since the ultrasonic array sensor performs electronic scanning, it is not necessary to mechanically move and scan the sensor itself within the effective visual field range, unlike the case where a single focus sensor is used.

Next, FIG. 4 is a system diagram showing an example of a measurement system for detecting a welding state of an underwater object using an ultrasonic array sensor. In this figure, the electronic scanning linear array sensor 9 is located in front of the welding torch 1 in the moving direction and above the underwater welding portion 16 and is arranged orthogonal to the welding line. Then, an ultrasonic wave is transmitted downward from the sensor 9, a reflected wave signal from the welding portion is received as an analog signal by the ultrasonic pulser / receiver 17, and the analog signal is converted by the A / D converter 18. At the same time as obtaining the contour image of the vertical section by the processing by the computer 19, information accumulation and feedback processing when the sensor 9 is moved in the welding line direction are performed. Next, based on these results, the motor driver 20 responds to the change in the positional relationship between the sensor 9 and the welding portion 16 so that the position of the welding torch 1 is always at an appropriate position on the welding line. Is performed.

By the way, in the ultrasonic B-scope measurement, the outline is blurred and unclear as a whole, and it is not easy to detect a slope portion, and moreover, many pseudo echoes (virtual images) may appear. In such a case, the information on the welded part 16 obtained from the similar case is input to the computer 19 in advance, and a correction process is performed by combining the information with the information from the welded part 16 obtained by the actual measurement. ,
In other words, by removing the extra signal by referring to the position of the ultrasonic wave, the measured value of the reflection intensity and the two-dimensional information obtained from them and the characteristics of the measurement target, and obtaining the accurate shape recognition result , The B scope image can be improved in image quality and sharpened.

[0012]

Next, the present invention will be described in more detail by way of examples.

Embodiment 1 90 vibrators, effective field of view 50 mm, center frequency 5 MHz
Sensor is installed vertically on the welding line, and two steel plates of 20 mm in thickness and 300 mm in length are joined to each other to measure the shape of the test piece when one to five layers of overlay welding are performed by underwater welding. did. FIG. 5A shows a photograph from above obtained in this manner. FIG. 5B is a sectional view corresponding to the position of the number shown in FIG.
The included angle was 60 ° and the root interval was 2 mm.

Embodiment 2 Using the same electronic scanning ultrasonic array sensor as in Embodiment 1,
With respect to the test piece used in Example 1, a B-scope image (a) of a V-groove shape without overlay when welded in water and a B-scope image (b) with overlay of three layers were measured. . The results are shown in FIG. 6 as (a) and (b). As can be seen from these figures, the contour line B of the B scope image,
The widths of b, c, d, e, f, g, and h are wide, and noise, ri, and nu are often seen due to virtual images, but the shape of the hypotenuse, ヲ, which was difficult to detect with the conventional method, It can be identified, and the profile in the depth direction of each welding layer can be recognized. The weld bead width when performing actual underwater welding is usually about 10 to 30 mm, and it is unlikely to exceed 50 mm at most, so if the effective measurement width of the ultrasonic array sensor is 50 to 70 mm, it is on the welding line It is not necessary to mechanically scan the array sensor itself having a rectangular cross section installed in the above, and a continuous B-scope image can be obtained by simply moving the array sensor as it is on the welding line.

Example 3 A B scope image (b) obtained by applying the three layers of overlay obtained in Example 2 was subjected to a computer correction process. The result is shown in FIG. In this figure, the outlines represented by the thin lines of the slopes and the center are the results after the processing, and it can be seen that the shape of the overlay welding can be determined quite clearly.

[0016]

According to the present invention, (1) an ultrasonic array sensor of an electronic scanning type or the like is used to obtain a B-scope image of a welded portion, so that a welded portion including a V-groove can be obtained without scanning the sensor. It can detect the position / shape, misalignment, route interval, welding line, etc. of the surface. (2) Improve real-time sensing performance in water (increase speed)
It is possible to feed back information at high speed, follow the welding line, and change the welding conditions. (3) It is compact and can be integrated with the welding nozzle, and can be applied to underwater thermal processing of narrow parts, etc. (4) By using in combination with the water curtain type underwater welding method, it is possible to contribute to the automation of wet type underwater welding and the improvement of welding quality associated therewith.
(5) By taking into account the characteristics of the measurement object (continuity of sides, known shapes known in advance) and removing extra ultrasonic signals, clearer shape recognition can be performed. Play.

[Brief description of the drawings]

FIG. 1 is an explanatory view of one example of the method of the present invention.

FIG. 2 is a perspective view of an electronic scanning ultrasonic linear array sensor.

FIG. 3 is a plan view of the sensor of FIG. 2;

FIG. 4 is a system diagram of the device of the present invention.

FIG. 5 is a photograph showing the shape of the test piece of Example 1 and a cross-sectional view of a portion corresponding to the number.

FIG. 6 is a B-scope image of a test piece welded part of Example 2.

FIG. 7 is a modified B-scope image according to the third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Welding torch 2 Nozzle outer periphery 3 Water curtain 4 Shielding gas 5 Cavity 6 Electrode wire 7 Base material 8 Arc 9 Ultrasonic array sensor 10 Ultrasonic beam 11, ... Transducer 12 Electronic switch 13 Acoustic lens 14 Matching layer 15 Transmission / reception circuit 16 Welded part 17 Ultrasonic pulser / receiver 18 A / D converter 19 Computer 20 Motor driver

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoji Ogawa 2217-14 Hayashi-cho, Takamatsu-shi, Kagawa Prefecture Inside SIC Industrial Technology Research Institute, Ministry of Economy, Trade and Industry (72) Inventor Takao Morita Hayashi-cho, Takamatsu-shi, Kagawa 2217-14 Ministry of Economy, Trade and Industry, National Institute of Advanced Industrial Science and Technology, Shikoku Institute of Industrial Technology (72) Inventor Minao Sakakibara 2217-14, Hayashi-cho, Takamatsu City, Kagawa Prefecture Reference) 4E001 AA03 BB09 DA01 DD02 DD04 DF08

Claims (4)

[Claims] 1. In performing wet underwater arc welding, an ultrasonic beam is rapidly moved in a non-contact manner while sequentially switching a plurality of transducers of an ultrasonic array sensor arranged on a welding line to change a welding state. An underwater welding method characterized by detecting and controlling a welding position and welding conditions based on the detection result. 2. The underwater welding method according to claim 1, wherein the unclear image obtained from the ultrasonic reflected wave of the ultrasonic beam is corrected to a clear image based on image information previously input to a computer. . 3. An underwater welding torch (1), an ultrasonic array sensor (9) arranged in front of the underwater welding torch, an ultrasonic pulsar receiver (17) for transmitting and receiving ultrasonic reflected waves, and an ultrasonic pulsar receiver (17). 17) an A / D converter (18) for A / D converting information from the A / D converter (18), a computer (19) for inputting information from the A / D converter (18) and performing arithmetic processing, and an output from the computer (19) An underwater welding apparatus comprising a motor driver (20) for operating an underwater welding torch (1) according to the following. 4. The underwater welding apparatus according to claim 3, wherein a water curtain is formed around the welding torch.