JPH04251671A - Method for automatic welding of consumable electrode system welding machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic welding method using a consumable electrode welding machine.

0002

[Prior Art] As a multi-layer welding method for parts to be welded, such as between pipe fittings or between a pipe and a nozzle joint, a consumable electrode welder (MAG welder, etc.) ) Welding methods are being considered to automate welding and save labor by performing automatic fold welding.

0003

[Problem to be solved by the invention] However, when a consumable electrode type welding machine is used, a large number of insulating glassy slags are generated at random positions on the surface of the weld bead, which is a major problem in automation. It has become an obstacle. In other words, when fold welding is performed using a consumable electrode welding machine, in order to prevent excessive build-up on the fold point side, arc welding to the consumable electrode at the fold point is conventionally done. The current supply was temporarily cut off, and then the arc current supply was restarted to ensure sound multilayer welding, but when the arc was restarted, glassy slag was present in the area facing the consumable electrode. There is a problem in that arc generation errors occur, and the consumable electrodes are buckled and deformed due to this arc generation error, making subsequent welding impossible. In order to improve arc restartability, welding power sources have recently been developed that have improved the characteristics of the welding power source and the current waveform when the arc is turned off so that the tip of the consumable electrode has a sharp edge after the arc is turned off. However, even if this welding power source is used to generate an arc, arc start errors due to slag cannot be resolved. For this reason, conventionally, the work of removing slag could not be omitted. Although it is possible to install a slag removal device to promote automation, it is difficult to employ this equipment because it complicates the welding system and greatly increases costs.

SUMMARY OF THE INVENTION An object of the present invention is to provide an automatic welding method using a consumable electrode welding machine, which eliminates arc errors during restart and performs sound automatic welding. There is something to do.

[0005]

[Means for Solving the Problems] In order to achieve the above objects, the present invention performs automatic fold-back welding using a consumable electrode welding machine from the welding start end to the welding end to perform multilayer welding on the welded part. In the automatic welding method using the consumable electrode welding machine, after the movement of the consumable electrode welding machine and the supply of arc current are temporarily stopped at the turning point, an ITV camera and an image processing device are used to detect the area on the bead facing the consumable electrode. The existence and shape of slag is determined, and if there is no slag, the consumable electrode welding machine is moved and the supply of arc current is restarted, and if there is slag, the consumable electrode welding machine is moved to the turning side while The ITV camera and the image processing device continue to perform slag determination, and the supply of arc current is restarted at a position where there is no slag.

[0006]

[Operation] Immediately after welding is completed, the movement of the consumable electrode welding machine and the supply of arc current are stopped, and the ITV camera and image processing device are used to determine the presence and shape of slag on the bead surface facing the consumable electrode. do. If there is no slag in the bead at this stop position, the movement of the consumable electrode welder and the arc are resumed. If there is slag at the stop position, move the consumable electrode welding machine to the turning side with the arc current supply stopped, and use the ITV camera and image processing device to check for slag on the bead surface facing the consumable electrode. Determine presence/absence and shape in real time. Then, the arc is restarted at a position where there is no slag. As a result, it becomes possible to automatically restart the arc without abnormally increasing the thickness of the weld layer near the turning point and without human intervention, and it becomes possible to automate multilayer welding using a consumable electrode welder.

[0007]

[Embodiment] A preferred embodiment of the present invention will be described below.

As described above, automatic fold welding is performed using a consumable electrode welding machine, and at the fold point, the supply of arc current is temporarily cut off, and then the supply of arc current is restarted.
In an automatic welding method that forms multiple weld layers on a welded part such as a pipe, glassy slag when the arc is restarted becomes a major obstacle.

[0009] Therefore, the present applicant has proposed that (a) slag is a substance that melts at a low temperature with respect to the filler metal (welding wire, etc.) and that it is easily remelted by arc heat; Focusing on the fact that slag does not occur all over the place, but rather locally and at random positions, we monitor the bead surface facing the consumable electrode using an ITV camera and image processing device. We have discovered a new automatic welding method using a consumable electrode welding machine that restarts arc welding from the area where there is no slag.

The applicant has devised a welding system shown in FIG. 1 to realize this welding method.

[0011] The welding system uses a consumable electrode (welding wire)
1, a torch 2 moving device (not shown), a welding power supply device 3, a lighting device 4, an ITV camera 5, an image processing device 6, and a welding control device 7. .

The torch moving device is configured to move the torch 2 back and forth between the welding start point and the end point of the groove line along the groove line formed in the welded member 11, and the welding power supply device 3 controls the torch moving device in conjunction with this, supplies a current of a specified voltage to the torch 2, and moves the consumable electrode 1.
An arc is generated to form a multilayer welding layer 8 on the groove. Both the lighting device 4 and the ITV camera 5 are mounted on a bracket (
The illumination device 4 illuminates the bead 9 facing the consumable electrode 1 of the torch 2, and the ITV camera 5 illuminates the bead 9 facing the consumable electrode 1 of the torch 2. The bead 9 is detected as an image signal, and the signal is transmitted to the image processing device 6. The image processing device 6
Image information from the camera 5 is processed to analyze the surface of the bead 9, and the analysis result is converted into a signal and transmitted to the welding control device 7 in real time. Basically, at the turning point, the welding control device 7 stops the movement of the torch moving device and gives a control signal to the welding power source device 3 to stop the supply of arc current, and then controls the image processing device. 6, if there is no slag 10 on the surface of the bead 9, the torch moving device and the welding power source device 3 are restarted to restart the movement of the torch 2 and the supply of arc current. Furthermore, if the result inputted from the image processing device 6 indicates that there is slag on the surface of the bead 9, the welding power supply device 3 is controlled to stop supplying the arc current, and the torch moving device is gradually moved to the turning side. Then, the ITV camera 5 and the image processing device 6 continue to monitor the surface of the bead 9, and when the result of no slag is input, the supply of arc current is restarted.

The welding start point and end point of the torch 2 relative to the groove are automatically determined by a position sensor installed at each of these points, or by a calculation that is attached to a torch moving device and used as a reference setting value. In addition, in pipe joints, the welding turning point is set beyond a predetermined welding start point to ensure sound lap welding.

Next, the operation will be explained.

[0015] When welding pipe fittings together using the above welding system, for example, the direction and height of the torch 2 relative to the grooves of these pipe fittings must be appropriately set to pre-programmed values for each layer. When the welding power supply device 3 is turned on, an arc current is supplied to the torch 2, and at the same time, the torch moving means is activated to start welding along the groove lines of the pipe joints. A position determining means such as a position sensor inputs a signal to the torch moving device, welding power supply device 3, lighting device 4, ITV camera 5, image processing device 6, and welding control device 7 at the turning point of the torch 2. The welding power supply device 3 and the torch moving device stop moving and supplying arc current upon receiving this signal, and the lighting device 4, ITV camera 5, and image processing device 6 are started upon receiving this signal. ITV camera 5
The surface of the bead 9 illuminated by the illumination device 4 is photographed and the signal is sent to the image processing device 6, and the image processing device 6 processes the signal into an image and displays the surface of the bead 9 facing the consumable electrode 1. The presence or absence of the slag 10 and its size are determined by image processing the surface condition of the slag 10. Then, the determination result is converted into a signal and input to the welding control device 7. In the welding control device 7, “
When a "no slag" signal is input, a control signal is given to the welding power supply device 3 and the torch moving device to activate them and restart welding.In addition, a "slag present" signal is input to the welding control device 7. If it is input, the ITV camera 5, illumination device 4, and image processing device 6 are left activated, a control signal is given to the welding power supply device 3 and the torch moving means, the supply of arc current is stopped, and the torch moving device is While the torch 2 is moving, the "no slag" signal is input from the image processing device 6 to the welding control device 7, and the welding control device 7 instantly A control signal is given to the welding power supply device 3 to restart the supply of arc current. As a result, normal arc welding is restarted. Once the arc is generated, the slag 1 on the surface of the bead 9
0 is melted by arc heat, and subsequent welding continues satisfactorily. Therefore, the welding layer thickness immediately after turning is set to normal, the arc start error when restarting the arc is eliminated, and welding by the consumable electrode type welding machine (torch 2) is started.

In the description of the embodiment, the illumination device 4, ITV camera 5,
Although we have explained how to start the image processing device 6, basically only the welding control device 7 is started using the control signal from the position detection means.
Other lighting devices 4, ITV cameras 5, and image processing devices 6 are
It is also possible to start it together with the welding power supply device 3 from the beginning.

[0017] Also, when turning around, only the arc is stopped and the torch moving means continues to move, while the I
The surface of the bead 9 may be monitored using the TV camera 5 and the image processing device 6, and the arc may be restarted at a position where there is no slag 10. Furthermore, there are no restrictions on the positions of the ITV camera 5 and lighting device 4 as long as the slag can be recognized.

[0018]

[Effects of the Invention] In summary, according to the present invention, it is possible to perform sound automatic welding using a consumable electrode type welding machine, and the welding can be performed unmanned, which is an excellent effect.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an automatic welding system according to the present invention.

[Explanation of symbols]

1. Consumable electrode (welding wire) 2. Torch, a consumable electrode type welding machine 5 ITV camera 6 Image processing device 9 Bead 10 Slag

Claims (1)

[Claims] [Claim 1] In an automatic welding method using a consumable electrode welding machine, the consumable electrode welding machine performs automatic fold welding from the welding start end to the welding end, and performs multi-layer welding on the welded part. After the movement of the consumable electrode welding machine and the supply of arc current are temporarily stopped, the presence or absence of slag on the bead facing the consumable electrode is determined using an ITV camera and an image processing device, and if there is no slag, the consumable electrode welding machine movement and supply of arc current are resumed, and if there is slag, the consumable electrode welding machine is moved to the turning side in that state, and the above-mentioned ITV camera and image processing device continue to determine the presence or absence of slag, An automatic welding method using a consumable electrode welding machine, characterized in that the supply of arc current is restarted at a position where there is no slag.