JP2796892B2 - Unmanned welding method for UO steel pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to inner or outer welding of UO steel pipe.

[0002]

2. Description of the Related Art Conventionally, UO steel pipes have been mainly
Line pipes having an outer diameter of about 0 mm and a thickness of about 6 to 40 mm are manufactured. In manufacturing this line pipe, the inner and outer surfaces are welded.
In order to secure required characteristics and obtain high efficiency, a multi-electrode submerged-arc welding method is employed. Therefore, as the welding work on the inner surface and the outer surface, there is a wide variety, and adjustment and monitoring work with advanced skills are indispensable, and part of the work has been automated, but the entire work has been automated. The actual situation is that there is no such thing so far, and many people are deployed and hand-worked. Moreover, the contents of the work are classified into handling work associated with welding, setting of welding conditions, adjustment work, monitoring of welding conditions, and monitoring of welding equipment and welding abnormal phenomena, and are extremely wide-ranging.

[0003] The specific contents of this are as follows: (1) Handling operations involved in welding include moving a pipe, positioning a pipe, positioning a pipe butt according to the amount of twist of the pipe, and setting a welding head (torch). Alignment to welding start position and pipe butt, spraying flux and collecting unmelted flux, welding start and stop, groove position profiling (visual profiling with spots), slag treatment of both pipe ends, after welding There is a wire-tipped cut. (2) In setting and adjusting welding conditions, current, voltage and speed are adjusted while actually operating or welding. (3) Monitoring of welding conditions and monitoring of welding equipment and abnormal welding phenomena includes monitoring the actual values of welding conditions of current, voltage, and speed and the presence or absence of fluctuations with special instruments, and also wire-feed and flux-feed. Similarly, the load status of each device such as feed, pipe movement, welding head movement, etc. is monitored by a dedicated instrument.
The occurrence of abnormalities such as arc exposure and burn-out due to insufficient flux is judged visually or by sound. These listed operations alone are extremely large. Therefore, in the conventional welding process, personnel have to be allocated for each process, and in general, the welding process often becomes a bottleneck in production efficiency, so that the welding line is often used. Are required, and more and more personnel are required. This is a process for which significant reduction in personnel by automation is highly desired.

[0004]

Heretofore, there has been a problem that a large number of personnel are required in the welding process due to the extremely large number of operations as described above. And that UO
To fully automate the welding of steel pipes, the following issues must be addressed.
is there. That is, (1) the amount of twist of the UO steel pipe (the screw at the weld groove)
And how to perform automatic welding. (2) Automatic setting of welding conditions in setting and adjusting welding conditions
How stable is reset? (3) How to detect and respond to abnormal welding
Is the biggest challenge. The present invention has been made in view of this problem.
Instead of a series of manual operations for inner or outer welding in the steel pipe manufacturing process, complete automation of UO welding is achieved, which will significantly reduce the number of personnel and will not provide fully automated UO welding technology that achieves high productivity. It is assumed that.

[0005]

In order to solve the above-mentioned problems, the present invention provides a dedicated robot for the entire welding machine by using various automatic devices utilizing a laser, an image processing device, etc., for a series of handling operations for inner or outer welding. The setting and adjustment of welding conditions is done by using a computer preset method to eliminate the need for setting and adjustment. In addition, for monitoring during welding, detection of open arc and burn-through by CCD camera and image processing, and A fully automatic welding is made possible by automatically monitoring the load current and the current, voltage, speed and the like of the welding equipment by a monitoring device that continuously checks the welding current. That is, the present invention
Laser welding on inner or outer surface of O steel pipe
The slit light is projected on the welding groove shape part, and the CCD camera
The center position of the groove was detected and measured by the image processing device.
Send the amount of twist for each pipe to the welding machine via the computer
Position of the welding head, and set welding conditions and welding
Preset control by matching with voltage and welding voltage
Arc control is achieved by parallel control with direct feedback control.
Presets to prevent burn-through and open
Detects the amount of light with a CCD camera and performs image processing
In which the welding abnormality is judged, and automatic welding is continuously performed .

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is an overall conceptual diagram showing an inner surface welding device in a UO manufacturing process. First, as an automatic handling equipment for welding work, the movement and positioning of pipes are performed by the conveyor roll 1. By increasing the speed and automatic sequence of each, automatic operation of pipe loading and unloading can be accelerated. I can plan. In this case, further acceleration / deceleration control can be performed in the conveyor roll 1 to improve the stopping accuracy, and the pipe can be positioned with high accuracy. Next, the welding head position is adjusted to the groove position by the turning roll 2 and the groove detection sensor-3. In this case, positioning according to the amount of twist of the pipe is performed. FIG. 2 shows details of the groove position detection method for this purpose.

FIG. 2 is a diagram showing a groove position detecting method using a light cutting method. The laser emitted by the laser oscillator 12
The laser light is turned into slit light 13 by the lens and projected on the detection object 14. Slit light 1 on detection object 14
CCD camera 15 centering on the portion where 3 is projected
To image from a predetermined angle. The image signal obtained by the CCD camera 15 is image-processed by the image processing device 16 and the shape and position of the groove are displayed on the monitor 17 as the cross-sectional shape A. In this image processing, in order to obtain the slit light 13 projected on the measurement object 14 as a cross-sectional shape on the image, binarization processing, that is, “white” when the luminance on the image exceeds a certain set value After that, a process of displaying the section shape A by setting it to “black” is performed.
Through the above processing, the white line image data of the obtained image is further subjected to primary or secondary differentiation processing to determine the groove edge 14a or the groove bottom position 14b. In this way, the slit light from the laser is applied to the groove, and CC
The center position of the groove is detected by the D camera and the image processing device, and the amount of twist measured for each pipe measured in advance is computed.
The position of the welding head relative to the groove position according to the amount of torsion of the pipe is determined by moving the position of the welding head, which is integrated with the groove center position detection device, to the welding machine via a welding machine. Also, the groove surface properties, groove width, and temporary bead
± 1 mm by adding an algorithm for shape pattern recognition, abnormal part recognition, etc.
High accuracy detection performance can be secured. In addition, a welding head automatic driving device 4 is provided, and a high rigidity type non-adjustable welding head 5 is provided at the tip thereof. In this apparatus, the welding start position of the welding head 5 is accurately adjusted to the welding start position by a pipe end detection sensor and drive system speed control. In addition, start and stop of welding and welding flux 2
As for the stop of spraying 1 and the stop of recovery of unmelted flux, automatic welding start and stop and stop of automatic flux spraying and collection start can be stopped by a pipe end detection sensor and an automatic sequence of the welding head. Automatic groove position copying during welding
A method of directly following the groove by inserting the groove copying roll 11 into the groove, or applying the slit light by the aforementioned laser to the groove, and using a CCD camera and an image processing device to center the groove. The method is performed by detecting the position. Further, an automatic welding head level control device 6 for the welding end portion is provided. FIG.
Reference numeral 9 denotes an automatic slag pushing device for pushing slag generated on the tab plate 29 and at the end of the pipe into the pipe, and reference numeral 10 denotes an automatic wire-cutting device for welding wire-polished balls and cutting for each time welding is completed. At the same time, the shape of the wire after cutting and the level of the wire with respect to the mother tube 22 are simultaneously ensured so that a good welding start can be made when the next pipe is welded. As described above, various automatic devices utilizing lasers, image processing, and the like have made it possible to make the entire welding machine a dedicated robot.

Secondly, in setting and adjusting the welding conditions, an automatic presetting device 8 for stabilizing the welding conditions is provided for automatic presetting and stabilization of the welding conditions, and preset control by abutting the welding condition set value with the welding voltage. A parallel control system of direct feedback control of welding voltage and welding voltage enables high-speed response and high stability of wire feed control, and realizes a stable automatic preset of arc. FIG.
As shown in the figure, as the relationship between the preset control ratio and the voltage fluctuation, a stable state is shown in which the voltage fluctuation is small at around 50% of the preset control ratio.

Thirdly, monitoring of abnormal welding phenomena, the example shown in FIG. 4 is "burn-through" which is a welding abnormality in inner surface welding.
This is a welding abnormality detection device that detects the following welding abnormality. In the figure, reference numeral 18 denotes a welding torch, and 19 denotes a welding wire. Reference numeral 20 denotes a wire for feeding the wire-19.
A feeding roller 21 is a welding flux. 2
Reference numeral 5 denotes a supporting arm such as the welding torch 18, and reference numeral 26 denotes a welding cable, which can be automatically welded in a long steel pipe. 27 is a receiving stand for the mother pipe. Under such a structure, a monitoring device 28 such as a CCD camera equipped with an optical system composed of various filters is installed on the side surface of the welded portion directly below the torch to monitor the welding condition. It is something to do. The image processing device 31 is a monitoring device 28
, The light amount of the molten steel that has melted down is binarized and indicated as a bright portion, and the number of bright portion pixels, time measurement, and the like are performed. The system control device 32 gives an operation signal to the image processing device 31, the monitoring device 28, and the like, and turns on the indicator lamp 33 and the buzzer 34 based on the processing data of the image processing device 31, and sets in advance. The welding power source 35 and the welding head automatic driving device 4 are controlled by the sequence thus performed. Under such an operation, the monitoring device 28 detects only a light beam of a certain frequency, performs image processing on the detected light beam, determines that the burnout has occurred based on the light area and the duration of a certain light amount or more, and automatically stops welding. do.

FIG. 5 is a cross-sectional view showing a burn-through state, and shows burn-through 37 of molten steel. Further, FIG.
A welding abnormality detecting apparatus for detecting a welding abnormality "open arc" will now be described. That is, when an open arc occurs due to the shortage of the flux 21 at the time of molten steel, only a light beam of a certain frequency is detected by a CCD camera equipped with an optical system composed of various filters, and the detected light is imaged. After processing, the open area is determined based on the light area and the continuation time exceeding a certain light amount, and the welding is automatically stopped. In addition, the same applies to arc breaks and burn-in during welding. If arc breaks or burn-in occur, judgment is made based on the continuously measured current value, voltage value, duration, etc. Then, the welding is automatically stopped.

[0011] Further, automatic monitoring is performed by a monitoring device that continuously checks welding conditions and welding equipment. Actual values and fluctuations of welding conditions of current, voltage, and speed are sampled every moment. Take the relationship between the absolute value, fluctuation variation and time, and when a certain criterion is exceeded,
The occurrence position and the absolute value are displayed and recorded as an alarm, and at the same time, feed forward through a computer to a subsequent inspection process. Then, an average value and a variation value of the entire welding length are calculated, and when the frequency exceeds a certain frequency (number), the welding is automatically stopped. At the same time, it can be transmitted to a host computer and edited off-line as performance data. Furthermore,
For overload detection of each device such as wire feed, flux feed, pipe movement, welding head movement, etc., the load current of each device is detected, and when it exceeds a certain value, an alarm display and automatic welding stop are performed. doing.

[0012]

As described above, for a series of handling operations for the inner or outer surface welding of a UO steel pipe, the entire welding is made into a dedicated robot by various automatic devices, so that there is no need to adjust the welding conditions, and the welding time is reduced. The monitoring work has realized an extremely large number of personnel reductions through automatic monitoring, greatly improving labor productivity and stabilizing welding conditions.
It has great effects, such as quality improvement by fine-grained welding operation management, reduction of welding material cost, and improvement of working environment, and is industrially extremely advantageous.

[0013]

[Brief description of the drawings]

FIG. 1 is an overall conceptual diagram showing an inner surface welding device in a UO pipe forming process.

FIG. 2 is a diagram illustrating a groove position detection method using a light cutting method.

FIG. 3 is a diagram illustrating a relationship between a preset control ratio and a voltage change.

FIG. 4 is a diagram showing a welding abnormality detection device applied to the inner surface automatic welding of a UO steel pipe.

FIG. 5 is a cross-sectional view showing a burn-through state and an open arc state.

[Explanation of symbols]

 1 Conveyor roll, 2 Turning roll, 3 Groove detection sensor, 4 Welding head automatic driving device, 5 High rigidity type non-adjustment welding head, 6 Terminal trailing roll level automatic control device, 7 Abnormality detection sensor (CCD camera), 8 Welding condition stable type automatic presetting device, 9 Automatic slag pushing device, 10 Wire cutting device, 11 Groove roll, 12 Laser oscillator, 13 Slit light, 14 Measurement object, Reference Signs List 15 camera, 16 image processing device, 17 monitor, 18 welding torch, 19 welding wire, 20 wire feed roller, 21 welding flux, 22 mother pipe, 23 backing material, 24 support stand, 25 Support arm, 26 welding cable, 27 cradle, 28 monitoring device, 29 tab plate 30 spotlight, 31 image processing device (for burn-through detection), 31 'Image processing device (for detecting open arc) 32 System control device, 33 Indicator light, 34 Buzzer, 35 Welding power source, 36 Traveling device, 37 Molten molten steel, 38 Open arc, 39 Tab Board.

────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Shinji Asanuma 1 Kimitsu, Kimitsu City, Chiba Prefecture Nippon Steel Corporation Kimitsu Works (56) References JP-A-63-123597 (JP, A) JP-A-59-92173 (JP, A) JP-A-62-134191 (JP, A) JP-A-63-171270 (JP, A) JP-A-55-70476 (JP, A) JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B23K 9/00 B23K 37/00 B23K 26/00

Claims (1)

(57) [Claims] 1. In a welding of an inner surface or an outer surface of a UO steel pipe, a slit light by a laser is projected onto a welding groove shape portion.
And the center position of the groove by CCD camera and image processing device.
Detects and measures the amount of torsion for each pipe using a computer
To the welding machine through the
Preset by comparing the contact condition set value with the welding voltage
Control of direct control and direct feedback control of welding voltage
Presets the arc and controls the melting during welding.
Fall and open arc are illuminated by CCD camera
Is detected and image processing is performed to determine welding abnormalities.
An unmanned welding method for UO steel pipes, characterized by performing automatic welding .