JP2005342723A - Submerged arc welding method of steel plate, and submerged arc welding machine for manufacturing uoe steel tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a submerged arc welding method of a steel plate which is capable of suppressing occurrence of defective welding such as slag inclusion by stabilizing arc and realizing excellent quality of a weld part and suitable for manufacturing a UOE steel tube, and a submerged arc welding machine for manufacturing the UOE steel tube. <P>SOLUTION: When performing the submerged arc welding of both ends of a steel plate 1 pressed in an O-shape by a submerged arc welding machine having electrode wires 6a-6b, the array interval of the electrode wires 6a-6b is monitored by a monitoring device 7 comprising image pickup devices 8 to pick up images of the electrode wires 6a-6b, an image processing device 9 to obtain the image data by performing the image processing of the signal output from the image pickup devices 8, a determination device 10 to determine whether or not the array interval of the electrode wires 6a-6b is within an adequate range based on the image data obtained by the image processing device 9, and a display device 11 to display the result of determination of the determination device 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a steel plate submerged arc welding method used when manufacturing a UOE steel pipe. The present invention also relates to a submerged arc welder for manufacturing UOE steel pipes.

  As shown in FIG. 4, UOE steel pipes used for chemical plant piping, natural gas or oil transportation piping, and the like are edge milled (beveled) at both ends of the steel plate 1, and then the steel plate 1. In general, the steel plate 1 is press-molded in order into a C shape, a U shape, and an O shape, and then both end portions of the steel plate 1 are welded by a submerged arc welding machine 2. FIG. 5 shows an example of a submerged arc welding machine described in Patent Document 1, for example, used when manufacturing such a UOE steel pipe. In the figure, reference numeral 3 denotes a flux supply tube, 4 denotes a contact tip, 6a to 6d denote electrode wires protruding from the tip of each contact tip 4, and these electrode wires 6a to 6d are steel plates press-formed into an O shape. 1 are arranged along the central axis direction. The reason why the electrode wire of the submerged arc welding machine is multi-electrode is to increase the heat input during welding, improve the welding speed, improve the quality of the welded portion, and the like.

In order to improve the quality of the welded part, such as the strength and toughness of the parts where both side ends of the steel plate 1 are welded by such a submerged arc welder, an arc generated at the tip part of the electrode wires 6a to 6d is used. It is necessary to prevent the occurrence of welding defects such as slag entrainment as much as possible by stabilizing it so that the direction does not change or break, and for that purpose, an appropriate range determined by welding conditions such as welding current It is necessary to maintain the arrangement interval of the electrode wires 6a to 6d. Moreover, when the arrangement | positioning space | interval of electrode wire 6a-6d remove | deviates from the appropriate range, it is necessary to readjust the arrangement space | interval of electrode wire 6a-6d.
JP-A 63-260676

However, as the welding progresses, the contact tips are worn or the electrode wires are warped, and the arrangement interval of the electrode wires may inevitably fluctuate, making it difficult to stabilize the arc. .
The present invention has been made paying attention to such problems, and by stabilizing the arc, it is possible to suppress the occurrence of welding defects such as slag entrainment and to improve the quality of the welded portion. An object of the present invention is to provide a submerged arc welding method for a steel sheet and a submerged arc welding machine for manufacturing a UOE steel pipe, which are suitable for manufacturing a UOE steel pipe.

  In order to achieve the above object, a submerged arc welding method for a steel sheet according to the present invention according to claim 1 is configured such that both end portions of a steel sheet press-formed into an O shape are formed by a submerged arc welding machine having a plurality of electrode wires. When performing the submerged arc welding, the both end portions of the steel sheet are submerged arc welded while monitoring the arrangement interval of the electrode wires with a monitoring device.

  A submerged arc welder for manufacturing a UOE steel pipe according to a second aspect of the present invention is a submerged arc welder for manufacturing a UOE steel pipe used when manufacturing a UOE steel pipe, and includes a welding machine body having a plurality of electrode wires, An imaging device that images the electrode wire, an image processing device that obtains image data by performing image processing on a signal output from the imaging device, and an array of the electrode wires based on the image data obtained by the image processing device A determination device that determines whether or not the interval is within an appropriate range and a display device that displays a determination result of the determination device are provided.

A submerged arc welder for manufacturing a UOE steel pipe according to a third aspect of the present invention is the submerged arc welder for manufacturing a UOE steel pipe according to the second aspect, wherein the arrangement interval of the electrode wires is outside an appropriate range. An alarm device for issuing an alarm is further provided.
A submerged arc welder for manufacturing a UOE steel pipe according to a fourth aspect of the present invention is the submerged arc welder for manufacturing a UOE steel pipe according to the second or third aspect, wherein the arrangement interval of the electrode wires is out of an appropriate range. In some cases, the apparatus further comprises an interval adjusting device for adjusting the arrangement interval of the electrode wires within an appropriate range.

  According to the present invention, when the arrangement interval of the electrode wires is out of the proper range during welding, the welding operation is stopped and the arrangement of the arrangement intervals of the electrode wires is readjusted manually. By stabilizing, the occurrence of welding defects such as slag entrainment can be suppressed, and the welded part quality can be improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same part as what was shown in FIG. 5, and detailed description of the part is abbreviate | omitted.
In FIG. 1, the outline | summary of the submerged arc welding machine for UOE steel pipe manufacture of this invention is shown. In the figure, reference numeral 5 denotes a welding machine body, 8 denotes an imaging device such as a CCD camera that images the electrode wires 6a to 6d, and 9 performs image processing on an image signal output from the imaging device 8 to obtain image data. The obtained image processing apparatus 10 is a determination apparatus that determines whether the arrangement interval of the electrode wires 6a to 6d is within an appropriate range based on the image data obtained by the image processing apparatus 9, and 11 is the determination apparatus. It is a display device that displays the determination result of the device 10. In the present invention, the imaging device 8, the image processing device 9, the determination device 10, and the display device 11 are collectively handled as the monitoring device 7. Moreover, the submerged arc welding machine 20 for UOE steel pipe manufacture of this invention is the alarm apparatus 12 which issues a warning, when the determination apparatus 10 determines with the arrangement | positioning space | interval of the electrode wires 6a-6d being out of an appropriate range, and the electrode wire 6a. An interval adjusting device 13 that adjusts the arrangement interval of the electrode wires 6a to 6d within the appropriate range when it is determined that the arrangement interval of .about.6d is out of the appropriate range may be provided.

  FIG. 2 shows an enlarged view of the both-side ends of the steel plate 1 press-formed into an O shape by submerged arc welding using electrode wires 6a to 6d attached below the welding machine body 5. FIG. In the figure, reference numeral 14 denotes a base material, 15 denotes a flux, and 16 denotes a molten pool. The main role is to ensure the penetration of the leading electrode wire 6a and the electrode wire 6b on the second surface from the leading edge. The main role is that the electrode wire 6c from the top surface to the third surface forms a weld bead, and the electrode wire 6d from the top surface to the fourth surface forms a finish bead.

  According to such a configuration, since the determination result of the determination device 10 that determines whether or not the arrangement interval of the electrode wires 6a to 6d is within an appropriate range is displayed on the display device 11, a ruler is applied to or displayed on the display device 11. The arrangement interval can be measured by, for example, placing a scale on the device 11. Then, it can be determined at a glance whether or not the arrangement interval of the electrode wires 6a to 6d is within an appropriate range. This arrangement interval can also be automatically measured in the image processing apparatus 9 or the determination apparatus 10. This eliminates the need to directly determine whether or not the arrangement intervals of the electrode wires 6a to 6d are within the appropriate range, so the welding operation is stopped and the arrangement intervals of the electrode wires 6a to 6d are readjusted. By stabilizing the arc, including the case where manual measures such as these are separately taken, the occurrence of welding defects such as slag entrainment can be suppressed, and the quality of the welded portion can be improved.

  Further, when the alarm device 12 is provided, an alarm is issued from the alarm device 12 when the arrangement interval of the electrode wires 6a to 6d is out of the proper range during welding, so that a person is not constantly monitoring the display device 11. However, it is possible to include a case where manual measures are taken such as stopping the welding operation and adjusting the arrangement interval of the electrode wires 6a to 6d when an alarm is issued.

When the interval adjusting device 13 is provided, when the arrangement interval of the electrode wires 6a to 6d deviates from the appropriate range during welding, the arrangement interval of the electrode wires 6a to 6d is automatically within the appropriate range by the interval adjusting device 13. Since the adjustment is performed again, the occurrence of welding defects such as slag entrainment can be suppressed, and the quality of the welded portion can be improved. Specifically, in order to adjust the arrangement interval of the electrode wires 6a to 6d, an actuator (not shown) such as a stepping motor or a servo hydraulic valve is attached to one or more of the electrode wires 6a to 6d in a direction in which the arrangement interval increases or decreases. The target value of each arrangement interval of the electrode wires 6a to 6d and the image data obtained by the image processing device 9 stored in the image processing device 9, the determination device 10 or the interval adjusting device 13 are stored. Compared with the actual value of each arrangement interval of the electrode wires 6a to 6d automatically determined based on the command, the interval adjusting device 13 issues a command to operate the actuator in a direction in which the actual value approaches the target value. You just have to put it out. The actuator is not limited to a stepping motor or a servo hydraulic valve, and the target value of the arrangement interval is not limited to a constant, and may be changed according to welding conditions such as a welding current. As shown in FIG. 2, for each arrangement interval of the electrode wires 6 a to 6 d, one method is to measure a, b, and c at the boundary between the flux and the atmosphere. Of course, e, f, and g may be measured further upward by d.
FIG. 3 shows changes in the welding current and the welding voltage when the arrangement intervals of the electrode wires 6a to 6d are set to 20 mm, 15 mm, and 13 mm as a trial.

As shown in FIG. 3, when the arrangement interval of the electrode wires 6a to 6d is set to 20 mm, changes in current and voltage increase. As a result, as shown in Table 1, the number of occurrences of slag entrainment defects increases, and it becomes difficult to improve the quality of the welded portion of the portion where both end portions of the steel plate 1 are welded by the submerged arc welding machine. On the other hand, when the arrangement interval of the electrode wires is set to 15 mm or less, changes in current and voltage are reduced, and as shown in Table 1, the number of slag entrainment defects is reduced. Therefore, when the both ends of the steel plate 1 press-formed into an O shape are welded by a multi-electrode submerged arc welding machine, it is preferable that the arrangement interval of the electrode wires is 15 mm or less.
In the above-described embodiment, the electrode wire of the submerged arc welding machine is imaged by an imaging device such as a CCD camera, and it is determined whether or not the arrangement interval of the electrode wires is within an appropriate range. For example, a laser distance meter or the like may be used as means for measuring the arrangement interval.

It is a figure for demonstrating the outline | summary of the submerged arc welding machine for UOE steel pipe manufacture of this invention. It is a figure which expands and shows a mode at the time of submerged arc welding with four electrode wires. It is a figure which shows the change of the welding current and welding voltage at the time of setting the arrangement | sequence space | interval of the electrode wire of a submerged arc welding machine to 20 mm, 15 mm, and 13 mm. It is a figure for demonstrating the manufacturing process of a UOE steel pipe. It is a figure which shows an example of the submerged arc welding machine used when manufacturing a UOE steel pipe.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel plate 2 Submerged arc welding machine 3 Flux supply pipe 4 Contact tip 5 Welding machine main body 6a-6d Electrode wire 7 Monitoring apparatus 8 Imaging apparatus 9 Image processing apparatus 10 Judgment apparatus 11 Display apparatus 12 Alarm apparatus 13 Spacing adjustment apparatus 14 Base material 15 Flux 16 Molten pool 20 Submerged arc welding machine for UOE steel pipe manufacturing

Claims (4)

  When both ends of a steel sheet press-formed into an O shape are submerged arc welded by a submerged arc welding machine having a plurality of electrode wires, the both ends of the steel sheet are monitored while monitoring the arrangement interval of the electrode wires with a monitoring device. A submerged arc welding method for steel sheets, characterized in that submerged arc welding is performed.   A submerged arc welding machine for manufacturing a UOE steel pipe used when manufacturing a UOE steel pipe, a welding machine body having a plurality of electrode wires, an imaging device for imaging the electrode wires, and a signal output from the imaging device An image processing device that obtains image data by performing image processing, a determination device that determines whether the arrangement interval of the electrode wires is within an appropriate range based on the image data obtained by the image processing device, A submerged arc welding machine for manufacturing a UOE steel pipe, comprising: a display device that displays a determination result of the determination device.   The submerged arc welding machine for manufacturing a UOE steel pipe according to claim 2, further comprising an alarm device that issues an alarm when the arrangement interval of the electrode wires is outside an appropriate range. Submerged arc welding machine.   4. A submerged arc welding machine for manufacturing a UOE steel pipe according to claim 2 or 3, wherein the arrangement interval of the electrode wires is adjusted within the proper range when the arrangement interval of the electrode wires is outside the proper range. A submerged arc welding machine for manufacturing UOE steel pipes.

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