JP2721250B2 - Groove copying method and apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a groove copying method and apparatus in gas shielded arc welding.

[Conventional technology]

At present, there is a strong demand for fully automated and robotized welding processes in structures such as shipbuilding, bridges, and buildings.

In carrying out these, the most important issue is the establishment of a technique for detecting the position, width, height, etc. in the groove copying method.

In arc welding, the high heat generated by the arc is used to melt, solidify, and join the filler metal and base metal. Before welding starts and during welding, the groove deforms due to heat distortion, and the groove position, width,
Height changes. Therefore, in order to perform the groove following control, it is necessary to detect the position, width and height of the groove as close to the arc as possible, including deformation during welding.

As a conventional groove detection technique, an arc sensing method represented by JP-A-62-230476 has been put to practical use. In this method, the welding torch 3 shown in FIG. 3 swings the torch 30 in the groove width direction, and the length of the wire 23 or the arc 24 at this time changes near the right end 27 and the left end 26 of the torch swing. Using the fact that the welding current changes from the left end to the right end and from the right end to the left end of the torch swing, the welding current difference 1 mm inside the right end SR = IR1-IR2, and the welding current difference 1 mm inside the left end SL = I
Based on L1-IL2, groove position detection is performed from the value of SR-SL,
This method detects the route interval from the value of R + SL, and is the most advantageous method for groove deformation during welding because groove detection is performed at the arc point.

As an optical method, a detection method represented by Japanese Patent Application Laid-Open No. 55-30339 is a method of irradiating a groove with a slit light, processing an image photographed by a television camera, and detecting a groove position. .

[Problems to be solved by the invention]

However, in the above arc sensing method, the swing of the torch must be increased in order to obtain a large change in welding current required for detecting a groove.

For this reason, when the plate thickness is small, the groove shoulder 29 is melted as shown in FIG. 8, and a necessary change in welding current does not occur, so that it is difficult to perform good arc sensing.

In addition, the conventional optical method is too large to use a television camera or a slit light source device, and is not easy to handle. In addition, image processing takes time, and there is a problem in control response time. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned drawbacks and to enable stable continuous welding with respect to a change in groove.

[Means for solving the problem]

The present invention provides, in gas shielded arc welding, two laser oscillators each having a wavelength of 0.7 μm or more and a laser oscillator having a wavelength of 0.7 μm or more, which are arranged at the groove position 50 to 300 mm in front of the welding arc and on the left and right of the welding line. Using a laser displacement meter with an integrated receiver equipped with a filter that transmits light, the bevel is controlled by controlling the torch position so that the torch position is always equidistant from the left and right groove surfaces. In addition to performing line profiling, the groove width profiling is controlled by controlling the welding speed and the swing width corresponding to the groove root gap measured by the laser displacement meter, and in a groove profiling apparatus of gas shield arc welding, Laser oscillator with wavelength of 0.7μm or more and 0.7μm
A laser displacement meter integrated with a receiver equipped with a filter that transmits light of the above wavelengths, one each at the torch side of the welding line, at a position 50 to 300 mm in front of the welding arc, and at the left and right of the welding line A groove copying apparatus characterized by being arranged.

 Hereinafter, the present invention will be described in detail.

[Action]

FIG. 1 shows the configuration of the laser displacement meter used in the present invention.
The laser displacement meter 4 includes a laser oscillator 15, a laser light receiver 18, a filter 16, and a lens 17. The laser irradiation light 13 changes its distance until it is reflected by the groove inner surface 31 of the test plate 2. The output of the vessel 18 changes.

FIG. 2 shows a principle diagram of a groove copying method using the laser displacement meter of the present invention. Two laser displacement gauges 4a, 4b shown in FIG.
The laser beam oscillated from the left laser displacement meter 4a is set on the right and left sides of the groove welding line, and the right laser displacement meter is
The laser light oscillated from 4b hits the left wall of the groove, is reflected, and is installed so as to enter the light receiver of each laser displacement meter. The distance from each laser displacement meter to the reflecting surface is detected by the left and right laser displacement meters.
The difference between the output voltages of the left and right laser displacement meters is ± 0V. That is, control is performed so that the left and right measurement distances become equal. With this control, the torch position is maintained at the center of the groove interval.

In addition, in accordance with the change in the output voltage of either the left or right laser displacement meter, the groove width is controlled so that the appropriate swing width and welding speed corresponding to the change are obtained. In FIG. 2, the output voltage of the left laser displacement meter 4a is detected, and the swing width and the welding speed are also controlled.

However, as described above, the groove must be detected at a position as close to the arc as possible during welding. However, since the arc light is extremely intense, the reflected light of the laser displacement meter is disturbed, and it is difficult to detect the distance. .

FIG. 9 is a spectrum intensity distribution of the arc light. The arc light has a large light intensity at a wavelength of 0.3 μm or more and less than 0.7 μm.

Therefore, when the wavelength of the laser beam or the wavelength of the received light falls within this range, the detection becomes unstable due to the arc light.

By setting the wavelength of the laser light or the light receiving wavelength to a long wavelength of 0.7 μm or more, stable detection becomes possible even when the distance between the torch and the laser displacement meter is 50 mm.

When the distance between the torch and the laser displacement meter is long, it takes time to weld the detection point, and during that time, the groove is deformed due to thermal strain as described above, and the groove position and the route interval change. The distance between the torch and the laser displacement meter is 300m
In the range exceeding m, the error of the detection result becomes large and stable welding control becomes difficult.

 Hereinafter, embodiments of the present invention will be described in detail.

〔Example〕

FIGS. 4 and 5 are a front view and a side view of the welding apparatus used in the method of the present invention.
The torch 3 is attached to the tip of the swinging mechanism 10 via a torch position adjuster 32, and two laser displacement meters 4 are provided on the left and right through a laser displacement meter position adjuster 33 around the groove. (4a, 4b) It is attached to the traveling cart. Laser displacement meter 4
The outputs of a and 4b were input to a voltmeter and a pen recorder via an adapter, and a groove detection signal during welding was monitored.

Oscillator of laser displacement meter is 0.78 μm and receiver is 0.7 μm
The following filters that reduce the short wavelength light were used.

For comparison, a method using a laser displacement meter having a laser of 0.63 μm outside the present invention and a filter for attenuating short-wavelength light of 0.6 μm or less in the photodetector was also performed by the same apparatus as the method of the present invention.

6 and 7 are a front view and a side view, respectively, of a welding device used in the conventional method, and a monitor device.

In the welding device, the torch 3 was attached to the swing mechanism 10. 7 detects the swinging of the torch with the potentiometer 22, inputs the torch to the X-axis of the oscilloscope 21 via the potentiometer adapter 20, detects the welding current with the shunt 19, and inputs it to the Y-axis of the oscilloscope 21. . The arc sensing signal during welding was monitored.

The upward single-side welding was performed using the test materials and welding conditions shown in Table 1.

In the welding experiment, in the method of the present invention and the comparative method other than the present invention, the left and right moving mechanism 11 of FIG. 5 was automatically adjusted so that the outputs of the laser displacement meters 4a and 4b became ± 0 V while observing the voltmeter 7a of FIG. The width scanning is automatically adjusted to the welding speed and swing width corresponding to the route interval determined in advance according to the output displacement of the laser displacement meter 4a while observing the voltmeter 7b. The groove shown in FIG. 10 was welded.

The distance between the welding torch 3 and the laser displacement meter 4 was set to 30, 50, 300 and 500 mm by adjusting the mounting position of the laser displacement meter.

In the conventional method, while observing the oscilloscope 21 in FIG. 7, the right and left moving mechanism 11 in FIG. 7 is adjusted so that the above-mentioned SR and SL become equal, and welding is performed while correcting the left and right positions of the welding torch 3.

The groove is plate length L = 1500mm and plate width W = 5 as shown in FIG.
00mm, thickness t = 6mm, 25mm, groove angle θ = 50 ° (6t), 30 °
(25t), start side route interval G1 = (6t: 2mm, 25t: 4m)
m), a tapered groove with a root interval G2 on the end side = (6t: 4mm, 25t: 8mm) was used. The evaluation method is that the arc during welding is stable, welding can be performed continuously from start to end, the center of the bead width after welding is 1.5 mm or less from the center of the root interval, and the backside welding was possible Good, the arc during welding was unstable and the welding was interrupted
Those exceeding 1.5 mm were evaluated as defective. Second implementation result
It is shown in the table.

The method of the present invention, in which the distance between the laser beam and the received light wavelength is 0.78 μmm and the laser displacement gauge torch is 50 to 300 mm, enables observation of the groove position, good groove line tracing and groove tracing control, and continuous back wavelength welding. did it.

However, when the distance between the laser displacement gauge torches, which is out of the range of the method of the present invention, is 30 mm and 40 mm, it is too close to the arc light, so noise due to the arc occurs, and the groove position could not be detected and good welding could not be performed. .

When the distance between the laser displacement meter and the torch is 400 mm or 500 mm, the groove position can be detected.However, since the distance between the laser displacement meter and the torch is too far, the detected groove condition and the groove condition at the arc point are different. Inconsistency occurred and good copying control and continuous welding could not be performed.

Further, when the wavelength of the laser beam and the received light were 0.63 μm, the wavelength was close to the wavelength of the arc light, so that the laser beam was disturbed by the arc light and good profile control and continuous welding could not be performed.

Furthermore, in the conventional method, the groove shoulder melts during welding, and it is difficult to change the welding current required for arc sensing, so that stable copying control and continuous welding cannot be performed.

Further, it was confirmed that the results of welding in the downward posture and the vertical posture using the method of the present invention were as good as the upward posture.

〔The invention's effect〕

Advantageous Effects of Invention According to the present invention, it is possible to perform continuous and stable continuous welding with good line and width scanning control for changes in groove shape and route interval during welding, and in the future, large block joints such as bottom blocks and joints and bridges It can greatly contribute to improvement of groove profiling control technology for fully automatic and robotized welding processes.

[Brief description of the drawings]

FIG. 1 is a front view showing the configuration of a laser displacement meter used in the method of the present invention, FIG. 2 is a block diagram showing the principle of a groove copying method using the laser displacement meter of the present invention, and FIG. FIGS. 4 and 5 are schematic views showing the principle of a groove detection method using an arc sensic in a conventional method, FIGS. 4 and 5 are front and side views of a welding apparatus equipped with a laser displacement meter used in the embodiment, and FIG. FIG. 7 is a front view of the welding apparatus for performing arc sensing used in the example, FIG. 7 is a side view of the welding apparatus for performing arc sensing used in the embodiment with a monitor device, and FIG. 8 is a thin plate welded by arc sensing. FIG. 9 is a front view illustrating the molten state of the groove at the time, FIG. 9 is a graph of the spectral intensity distribution of the arc light, and FIG. 10 is a plan view of the groove used in the embodiment. 1: Backing material, 2: Test plate 3: Torch, 4, 4a, 4b: Laser displacement meter 5: Amplifier, 6: Comparator, amplifier IC 7a, 7b: Voltmeter, 8: Rail 9: Dolly, 10: Shaking Moving mechanism 11: Left and right moving mechanism, 12: Vertical moving mechanism 13: Rail irradiation light, 14: Laser reflected light 15: Laser oscillator, 16: Filter 17: Lens, 18: Laser receiver 19: Shunt, 20: Potentiometer adapter 21 : Oscilloscope, 22: Potentiometer 23: Wire, 24: Arc 25: Torch swing center, 26: Torch swing left end 27: Torch swing right end, 28: Groove 29: Groove shoulder, 30: Torch swing 31 : Inside surface of groove, 32: Torch position adjuster 33: Laser displacement meter position adjuster W: Width of test plate, L: Length of test plate t: Plate thickness, Q: Groove angle G1: Start route Interval G2: End route interval

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Toshio Aoki 5-1-1 Fuchinobe, Sagamihara-shi, Kanagawa Prefecture Nippon Steel Corporation 2nd Technical Research Institute (56) References JP-A-52-100354 (JP, A) JP-A-63-50109 (JP, A) JP-A-62-86974 (JP, U)

Claims (2)

(57) [Claims] In a gas shielded arc welding method, two laser oscillators each having a wavelength of 0.7 μm or more and two wavelengths of 0.7 μm or more are arranged at the groove position 50 to 300 mm in front of the welding arc and are disposed on the left and right of the welding line. Opening by controlling the torch position so that the torch position is always equidistant from the left and right groove surfaces using a laser displacement meter that is integrated with a light receiver equipped with a filter that transmits light A groove profiling method characterized by performing front line profiling, and performing groove width profiling by controlling a welding speed and a swing width corresponding to a groove root gap measured by a laser displacement meter. 2. A laser displacement meter comprising a grooved copying apparatus for gas shielded arc welding, wherein a laser oscillator having a wavelength of 0.7 μm or more is integrated with a light receiver having a filter transmitting light having a wavelength of 0.7 μm or more. , A groove copying apparatus, wherein one is provided at each of a torch side of a welding line, a position 50 to 300 mm in front of a welding arc, and left and right of the welding line.