JPS6117364A - Double electrode type narrow groove welding - Google Patents

Abstract

PURPOSE:To automate weld line copying and to improve its efficiency by positioning a preceding welding torch properly in a narrow groove and making a succeeding welding torch copy by a controlling signal used for position correction of the preceding welding torch. CONSTITUTION:A TV camera 17 photographs the weld zone of a preceding welding torch 3a, and deviation of the torch 3a in the groove is detected by arc light detecting sensors 9, 9. Information from these is inputted to a controlling device 21 and compared with a reference value, and a correction signal is given to the driving system of the preceding welding torch 3a to make the torch 3a follow up the proper position. The position of the preceding welding torch 3a is stored by a delay copy controlling device 28 and the succeeding welding torch 3b is followed up when welding advanced by the distance between the two torches 3a, 3b. Positional correction for this following-up is made by giving the same signal with that given to the driving system of the preceding torch 3a to the driving system of the succeeding welding torch 3b.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention particularly relates to a two-electrode narrow gap welding method for welding joints of thick plates.

[Conventional technology]

As is well known, one method for highly efficient welding of thick plate joints is to narrow the groove width and perform one pass welding for each layer.
This is called narrow gap welding. In addition, as a method for further increasing the efficiency of the narrow gap welding method, a two-electrode method in which two welding torches are arranged in parallel in the front and back can be considered, and it is expected that the efficiency will be approximately doubled.

[Problem that the invention seeks to solve]

However, according to the narrow gap welding method described above, the gap between the welding torch and the groove wall is usually as small as 2 to 5 mm.
Workers had to constantly monitor the welding situation and adjust the torch position (up and down, left and right, and tilt) with high precision.

On the other hand, in the case of the two-electrode method, this monitoring and adjustment is more frequent, so the adjustment requires a high level of skill.Moreover, since the monitoring requires one's attention, it is mentally taxing and only experienced workers can handle it. There wasn't. Therefore, although this two-electrode method is extremely effective as a high-efficiency welding method for thick-walled structures, the range of application is limited due to a lack of skilled workers, etc., and it has not been fully utilized.

The present invention has been made in view of the above circumstances, and enables one person to manage multiple joints by automating weld line tracing in thick-walled welded structures such as pressure vessels, thereby significantly improving efficiency and reducing costs. The purpose is to provide a two-electrode narrow gap welding method.

[Means for solving problems]

The present invention captures an image of the welded part of the preceding welding torch with a TV camera, processes the image to control the welding 1/-ch position to follow the appropriate position, and detects arc light at the upper end of the groove to point the arc. By controlling the welding torch angle around This is to imitate the row welding torch.

[For production]

First, the welded part of the preceding welding torch is imaged by a TV camera, and the image is processed to calculate the wire position and wire protrusion length in the groove, and the offset in the groove of the preceding welding torch is detected. Next, input this information into the control device,
The preceding welding torch always generates a correction signal to the drive system of the preceding welding torch by comparing it with a preset reference value. ,@Make it follow the proper position (in terms of top and bottom, left and right, and angle).

Next, the position of the preceding welding torch is memorized for a certain period of time, and when welding has progressed by the distance between both torches, the trailing welding torch is followed. By doing this, it is possible to fully automate the position control of the leading and trailing welding torches, which are important for welding deep and narrow I-shaped beam openings, and to improve the quality of thick plate multilayer welds and reduce costs. Embodiment] Hereinafter, a case in which an embodiment of the present invention is applied to a thick-walled cylindrical circumferential joint will be described with reference to FIG. 1 and FIGS. 2(a) and 2(b). Here, FIG. 1 shows an automatic torch position tracing method and a welding control method according to the present invention. Also, Fig. 2 (,) is a front view partially showing Fig. 1, and Fig. 2 (b) is a front view partially showing Fig. 1.
is a side view of the same figure (,). Note that the appended letter "a" in the member number indicates a component of the preceding welding torch, and the appended letter "a" indicates a component of the trailing welding torch.

First, Figures 2 (a) and (b) will be explained. In the figure, la and lb are base materials as thick-walled structures, and a backing metal 2 is provided on the back side. A preceding welding torch Ja and a trailing welding torch 3b are provided between the base materials Ia and lb. Welding wires 4a and 4b are provided at the tips of the preceding welding torch 3a and the trailing welding torch 3b, respectively.

These welding wires 4a, 4b are each fed by a feeding roller 5a.

5b. In addition, 6g in the figure.

6b is an arc produced by the preceding welding torch 3a and the trailing welding torch 3b, respectively, and 7a and 7b are arcs produced by the same torches 3a and 3, respectively.
This is the weld metal according to b.

Next, FIG. 1 will be explained. In addition, Figure 2 (,),
Components that are the same as those in (b) are given the same reference numerals and their explanations will be omitted. Further, only the drive system on the preceding welding torch side will be described here. 8a in the figure is a shield box. This shield box 8a includes an arc light detection sensor 9 that has a built-in light receiving element that always receives arc light on both sides of the torch on the upper surface of the groove and inside the groove and outputs a light reception signal by the photoelectric effect.
, 9 are provided. These sensors 9 have a narrow entrance path for receiving straight light and a function of emitting gas from this path for cooling and preventing the adhesion of welding fumes and the like. A transmission shaft 10 is attached to the preceding welding torch 6a on this shield box 88.
a, drive motor 12m, , 13 via 11th
& are concatenated. Here, one transmission shaft 10ald
The transmission shaft 11a is used for copying the torch 6& left and right (in the groove width direction), and the other transmission shaft 11a is used for copying the inclination angle of the torch 6a. The drive motors 12a and 13a are housed in a box 14th.

On this box 14a is a transmission shaft 1 for vertical copying of the torch 6a.
A driving motor 16e is provided via 5a.

A suitable filter is provided near the preceding bath welding torch 3a to allow an industrial TV camera to image the welding part of the torch 3a, and the field of view is fixed to the welding part and is linked to the torch 3&. It has become. Said TV camera 21
An image processing device 19 is connected to 7 via a cable 18 for transmitting a TV double signal. This device 19 binarizes the image of the welded part taken by the TV camera 17 (sets an appropriate reference value and processes the brightness distribution of the arc light into binary values of bright and dark), and converts the resulting 2 It functions to calculate the groove width, wire position, and wire protrusion length from the TV scanning line signal of the digitized image.

The image processing device 19 is connected to a control device 21 having the following two functions via a cable 20 for transmitting calculated data.

This device 21 is composed of a microcomputer and an input/output interface, and compares the information on the bevel, wire position, and wire protrusion length output from the image processing device 19 with preset reference values to determine the torch position (up, down, left, right, etc.). ) to always maintain a constant condition, and a welding torch angle tracing function to judge the signals from the arc light detection sensors 9, 9 and correct the deviation of the preceding welding torch 3a at the upper end of the groove. Here, to explain in detail the determination of the signals from the sensors 9, 9, if one of the sensors 9, 9 installed on both sides of the torch no longer receives arc light, move the preceding welding torch 3a in the direction in which it receives the arc light. let However, the torch 3a rotates in an arc around the arc point.

22 in the figure is an amplifier connected to the arc light detection sensor 9.9 via a cable 23 for transmitting a light reception signal. This amplifier 22 amplifies the transmitted weak light reception signal (current) and converts it into a voltage signal. Amplifier 2
2 and the control device 21 are connected by a cable 24 that transmits the amplified signal. The control device 21 and the drive motor 12a are connected to each other by a cable 25 that transmits a welding torch left/right scanning signal and a welding torch angle scanning signal. The control device @21 and the drive motor 161L are connected by a cable 26 that transmits welding torch up and down tracing signals. The control device 21 is connected to a delay copying control device 28 via a couple 27 that transmits a beveling signal outputted from the image processing device 19, a welding torch outputted from the control device 21, and a left/right and angle scanning signal.
is connected. This device 28 first controls the welding speed from the information during the groove, and then changes the position (vertical, horizontal, angle) of the preceding welding torch 3a for a certain period of time (the preceding welding torch Ja
, the time obtained by dividing the distance between the trailing welding torches 3b by the welding speed), and outputs a delayed tracing control signal to the trailing welding torch 3b. To be more specific about the control of the welding speed, the groove length between the leading welding torch 3 and the trailing welding torch 3b is stored and updated in accordance with the progress of welding, and the average groove length during this period is calculated. , the calculated average groove width is compared with a preset reference value, and if there is a difference, a differential voltage is generated and a command signal for an appropriate welding speed is output. To give an example of input/output timing, data during the groove is taken in every 51 m of welding, and a welding speed control signal is output every 20 welding lengths (approximately every 3 seconds).

A cable 29 is connected between the delayed scanning control device 28 and the driving motors 12b and 13b on the trailing welding torch side for transmitting left and right and welding torch angle scanning signals of the trailing welding torch 3b.
connected by. In addition, the delay copying control device 28
and the drive motor 16b are connected by a cable 30 that transmits a signal for vertical scanning of the torch 3b. A welding speed controller 32 is connected to the delayed tracing control device 28 via a couple 31 that transmits and receives welding speed signals. This controller 32 is connected to a transmission mechanism 34 having a turning roller drive motor via a cable 33 for transmitting a motor control signal, and a transmission mechanism 34 having a turning roller driving motor.
5 are I-order connected.

Next, the effect will be explained. First, the welded part of the preceding welding torch 3a is imaged by the TV camera 12, this is binarized by the image processing device 19, the bevel, the wire position, and the wire protrusion length are calculated from this image, and the arc light The detection sensors 9, 9 detect the deviation of the groove circle -9 of the preceding welding torch 3a. Next, this information is input to the control device 21, compared with a preset reference value, and a correction signal is issued to the drive system of the preceding welding torch 3a to constantly keep the preceding welding torch 3a in the proper position t (vertical, horizontal, angular). (in terms of). Next, the positions of the preceding welding torches 3& are stored for a certain period of time by the delayed tracing control device 28, and welding is performed by both torches 3a.

3b (the variation in welding speed is corrected), the trailing welding torch 3b is followed. Here, this tracking is performed by applying the same signal as the correction signal given to the drive system of the preceding welding torch 3a to the drive system of the trailing welding torch 3b,
This means that the position of the trailing welding torch 3b is corrected.

According to the present invention, the photographic image of the welding part of the preceding welding torch 3a and the torch position (up and down, left and right) of the image processing method are
The welding line tracing method of the preceding welding torch 3a is automated using the following tracing method and the torch angle tracing method of the arc source detection method, and the trailing welding torch 3b is delayed for a certain period of time to follow the welding line, thereby achieving welding by both torches 3a and 3b. Line tracing can be automated. Therefore, the base material 7a.

In addition to being able to improve the quality and efficiency of welding in 1b,
It is possible for one person to work on multiple joints, resulting in significant cost reductions.

In the above embodiments, the case where the present invention is applied to a thick-walled cylindrical circumferential joint has been described, but the present invention is not limited to this, and similar functions and effects can be obtained also in longitudinal welding.

In this case, the difference is that the former uses a turning roller to weld, while the latter uses a welding wheel equipped with a welding torch. The action and effect are exactly the same as in the case of .

In addition, the narrow gap welding method according to the present invention includes a method in which the arc is oscillated by giving the wire a wave-shaped bend in an unreasonable manner in order to prevent failure of fusion at the gap end, and a method in which the arc is oscillated by giving the wire a waveform bend in an excessive manner in order to prevent failure of fusion at the end of the gap. A method in which the arc is oscillated by a real wire has already been proposed, but since the molten pool in the welding part and the arc condition are basically the same, the present application can be applied to either method.

〔Effect of the invention〕

As detailed above, the present invention automates weld line tracing and allows one person to manage multiple joints, significantly improving efficiency and reducing costs, and is applicable to thick welded structures such as pressure vessels. A two-electrode narrow gap welding method can be provided.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of a two-electrode narrow gap welding method according to an embodiment of the present invention, Figure 2 (-) is a front view partially showing Figure 1. ) is a side view of the same figure (,). 1a, 1b...Base metal, Ja...Advanced welding torch, 3
b... Trailing welding torch, 4h, 4b... Welding wire, 5&, 5 b-... Feeding P-ra, 6*, 6b-arc, 7a, 7b-welding metal, 8m, 8b-shield box, 9
...Sensor, 10h, 10b, l1m. 11b115th, 15b - transmission shaft, 12m. 12b, l Ja, I Jb, 16 a, 16
b = drive motor, 27-TV camera, 18.20.
23.24.25.26.27.29.30.31.3
3... Cable, 19... Image processing device, 21...
- Control device, 22... Amplifier, 28... Delay copying control device, 32... Controller, 34... Transmission mechanism, 35... Turning roller.

Claims (1)

[Claims] In the two-electrode narrow gap welding method using a leading welding torch and a trailing welding torch, the welded area of the leading welding torch is imaged with a TV camera, and the image is processed to imitate the position of the leading welding torch to the appropriate position. By detecting the arc light at the top of the groove and following the welding torch angle around the arc point, the leading welding torch is appropriately positioned within the narrow groove, and the position of the trailing welding torch is delayed for a certain period of time. A two-electrode narrow gap welding method characterized in that the following welding torch is caused to follow the control signal used to correct the position of the preceding welding torch.