JP2001232471A - Method for detecting abnormality of arc rocking amplitude in narrow groove gma welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for detecting an abnormality of arc rocking amplitude in narrow groove GMA welding capable of automatically detecting the abnormality of arc rocking amplitude to easily save manpower and improve quality. SOLUTION: Whether the abnormality occurs in the rocking amplitude of an arc 7 or not is automatically judged by comparing the difference of a welding current value or the difference of a welding voltage value when the rocking position of the arc 7 exists in the left and right zones and when it exists at the central zone with a reference value. Thus, since the wear progress of a power feeding chip 2 and the generation of a failure of a wire oscillator 11 are quickly and automatically detected, periodic or continuous monitoring by an operator is not necessitated, the power feeding chip is exchanged at a suitable time, a troublesome adjustment concerned about in the case of continuing defective welding is also avoided, and unmaned welding for a long time is allowed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to narrow groove GMA welding and, more particularly, to a method for detecting an abnormal swinging width of an arc which is suitable for automatically operating a corrugated wire type narrow groove GMA welding apparatus.

[0002]

2. Description of the Related Art As a narrow groove GMA (gas metal arc) welding method, there is a wavy wire type narrow groove GMA welding method disclosed in Japanese Patent Publication No. 54-450. In this welding method, for example, as shown in FIG.
In the process of feeding the welding wire 6, a large wave-like deformation is given to the welding wire 6 by the wire oscillator 11, and the welding wire 6 that has passed through the welding torch 1 is fed from the tip of the power supply tip 2 provided at the tip of the torch 1. A large swing is automatically performed by the restoring force of the bending habit, so that the arc of the welded portion 21 reaches the side wall surface of the narrow groove 4 and a sufficient penetration can be obtained. High quality welding. In FIG. 9, reference numeral 3 is a base material, 10 is a wire swing control shaft, 15 is a welding head, 16 is a wire feed roller, 20 is a weld metal, and 22 is a lower block of the welding torch 1.

The present welding method is applied to welding of a main pipe of a power generation boiler and a pressure vessel such as an RPV for nuclear power generation. For example, main pipes such as a main steam pipe, a high-temperature reheat steam pipe, a low-temperature reheat steam pipe, and a main water supply pipe of a power generation boiler send high-temperature, high-pressure steam heated by a coil from a boiler to a turbine, and work with the turbine. This is a pipe for returning the steam after completion to the coil of the boiler again, so that it generally has a large-diameter and thick-walled pipe structure to withstand high temperature and high pressure. Also,
Since these pipes themselves are high temperature and high pressure, the amount of expansion and contraction when the boiler is started and stopped is large, and excessive stress is concentrated on the welded joint. Therefore, the welding of the main pipe from the boiler to the turbine must be performed with extremely high quality, and the welding work of the large-diameter thick pipe is usually continuous welding for several hours for a long time.

However, in the corrugated wire type narrow groove GMA welding method, since the arc is swung within a narrow groove of about 10 mm, control of the swing position and swing width of the arc is very important. For example, if the GMA welding torch is offset to the left in a narrow groove, the center of the arc swings to the left, so the left wall is too melted and an undercut occurs, and conversely, the right wall is sufficiently melted. Failure occurs. G
When the MA welding torch rises above the normal position within the narrow groove, the swing width of the arc becomes too large, so that the left and right walls are excessively melted, and an undercut occurs. Conversely GMA
When the welding torch is lowered from the normal position within the narrow groove, the swing width of the arc becomes too small, so that the right and left walls are not sufficiently welded, and a fusion failure occurs.

[0005] In order to enable automatic control of such an arc swing position and swing width, the present applicant has first performed control to perform left and right position scanning of the arc swing center and constant torch height scanning. A method was proposed. Such a conventional proposal calculates and estimates the arc swing position, determines the arc swing position while comparing it with the actually measured welding current waveform or welding voltage waveform, and then determines the right half cycle and the left half cycle of the arc swing. A groove tracing control method of performing left and right position tracing of arc oscillation so that the difference between the waveform integrated values of welding current or welding voltage is always constant, and an average value of welding current or welding voltage in one cycle of arc oscillation. This is a control method in which the swing width of the arc is made constant by correcting the torch height so as to match a preset reference value.

[0006]

By the way, when continuous welding is performed for a long time by a corrugated wire type narrow groove GMA welding apparatus, a wire hole (a power supply tip) of a power supply tip provided at the tip of a GMA welding torch is provided. The periphery of the hole) wears in the direction of arc swing, so that the size of the power supply tip hole gradually increases. If welding is continued in a state where the power supply tip hole is too large, the walls on both sides are melted excessively due to an increase in the arc swing width, and an undercut is generated. The power swinging tip, which has been worn, has been replaced as appropriate by periodically monitoring the arc swing state.

Further, if the wire oscillator fails and the welding wire is no longer deformed in a wavy manner, the arc swing stops and normal welding cannot be performed. If the welding is continued while the arc oscillation is stopped, reworking only the narrow groove requires a lot of work.From this point, it is important for the operator to monitor the arc oscillation amplitude. there were.

[0008] However, the welding method in which the operator must monitor the abnormality of the swinging width of the arc as described above is a factor that hinders labor saving in automatic welding and also causes a variation in welding quality. I was

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object the purpose of automatically detecting an abnormality in the swing width of the arc swing, thereby saving labor and improving quality.
An object of the present invention is to provide a method for detecting an abnormal oscillation width of an arc in MA welding.

[0010]

SUMMARY OF THE INVENTION The above-mentioned object of the present invention is to provide a large-amplitude corrugated plastic deformation to a welding wire by a wire oscillator, and the deformation causes the arc to oscillate with a large amplitude toward a groove wall. Wire type narrow groove GM
In A-welding, when the right and left position of the arc swing center and the constant torch height copying are being performed, the average welding current value or the average welding voltage value when the arc swing position is in the predetermined region on the right side is determined. The difference between the average welding current value or the average welding voltage value when the moving position is in the center predetermined region is SR, and the average welding current value or the average welding voltage value when the arc swing position is in the left predetermined region. And the difference between the average welding current value or the average welding voltage value when the swing position is in the center predetermined region is SL, and when the average value of these SR and SL is out of a preset range, the arc swing is performed. This is achieved by determining that the swing width is abnormal.

Alternatively, the maximum welding current value or the minimum welding voltage value when the oscillating position of the arc is in the right region, and the minimum welding current value or the maximum welding voltage value when the oscillating position is in the central region. The difference is SR, and the maximum welding current value or the minimum welding voltage value when the oscillating position of the arc is in the left region, and the minimum welding current value or the maximum welding voltage value when the oscillating position is in the central region. Is set as SL, and when the average value of SR and SL deviates from a preset range, it is determined that the arc swing amplitude is abnormal.

When the swing width of the arc changes, the welding current waveform and the welding voltage waveform change. As described above, the welding is performed when the swing position of the arc is in the left and right regions and when the arc is in the center region. By comparing the difference in the current value or the difference in the welding voltage value with the reference value, it is possible to automatically determine whether or not an abnormality has occurred in the swing width of the arc.
Therefore, the progress of the wear of the power supply tip and the occurrence of the failure of the wire oscillator can be quickly and automatically detected, and the operator does not need to monitor regularly or continuously. As well as humanization, welding quality can be improved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIGS.

First, an outline of a corrugated wire type narrow groove GMA welding apparatus according to this embodiment will be described. FIG. 1 is an overall configuration diagram of the welding apparatus, and FIG. 2 is an arc oscillation swing width abnormality in the welding apparatus. It is a schematic diagram of a control system for detection.

As shown in FIG. 1, in the process of feeding the small-diameter welding wire 6 by the wire feed roller 16, the wire oscillator 11 is largely oscillated left and right by the wire oscillating control shaft 10. A large wavy deformation is given to the welding wire 6. When the welding wire 6 passes through the elongated tube of the welding torch (narrow groove GMA welding torch) 1 and then protrudes from the tip of the power supply tip 2 provided at the tip of the torch 1, it becomes bent. Since the restoring force causes the welding wire 6 to automatically swing largely right and left, the arc 7 reaches the side wall surface of the narrow groove 4 and sufficient penetration can be obtained. Further, a welding current waveform of the arc 7 repeatedly and automatically oscillated by the welding wire 6 deformed in a wave shape is taken into the control device 12 by the current detector 14 to obtain a waveform as shown in FIG. As shown in FIG. 2, the control device 12 includes a DC amplifier 17,
An A / D converter 18, a control computer 19, and the like are built in, and a welding current signal taken from the current detector 14 and a welding voltage between the welding torch 1 and the base material 3 are transmitted to the DC amplifier 1.
7 and control computer 1 via A / D converter 18
Take in 9. The control computer 19 analyzes a welding current waveform or a welding voltage waveform, and detects an arc oscillation swing width abnormality described later. The control computer 19 is connected to a swing-width-abnormality indicator 26 so that a display at the time of occurrence of an abnormality can be performed.

As described above, the corrugated wire type narrow groove GM
In the A welding method, since the arc is swung within a narrow groove of about 10 mm, it is very important to control the swing position and swing width of the arc. In the present embodiment, as will be described later, automatic control is enabled by detecting an abnormality in the swing width of the arc based on changes in the welding current waveform and the welding voltage waveform. Therefore, first, the corrugated wire type narrow groove GM
The relationship between the arc swing state of A welding and the welding current and welding voltage will be described in detail with reference to FIGS.
However, FIG. 3 is a schematic view showing an arc swinging state in a narrow groove in the corrugated wire type narrow groove GMA welding, and FIG.
5 is a waveform diagram of welding current and welding voltage corresponding to FIG. 5, FIG. 5 is a schematic diagram showing an arc swing state when the welding torch is displaced in a narrow groove, and FIG. 6 is a welding current and welding voltage corresponding to FIG. FIG.

FIG. 3A shows a normal state in which the welding torch 1 is located at the center of the narrow groove 4 and the arc swings equally in the left and right directions. FIGS. 4A and 4B. Shows a welding current waveform and a welding voltage waveform in such a normal state.
In a corrugated wire type narrow groove GMA welding, a narrow groove bottom 5 is used.
Is a U-shape, as shown in FIG. 4 (a), the welding current is maximized at the left and right ends of the arc oscillation where the length of the welding wire 6 protruding from the power supply tip 2 is short, and the center of the arc oscillation where the projection length is long is shown. The welding current is minimized. Conversely, as shown in FIG. 4B, the welding voltage is minimum at the left and right ends of the arc swing where the protrusion length is short, and is maximum at the center of the arc swing where the protrusion length is long.

However, if the welding torch 1 shifts left or right in the narrow groove 4, the arc swing shifts left or right, so that the waveforms of the welding current and the welding voltage are shown in FIG.
It differs from (a) and (b). For example, FIG.
As shown in the figure, when the welding torch 1 is displaced to the left in the narrow groove 4, the left wall in the narrow groove 4 melts too much and generates an undercut, and the right wall is not sufficiently melted. Defective fusion occurs. In this case, the length of the welding wire 6 protruding from the power supply tip 2 is shorter at the left end of the arc oscillation than in the case of FIG. 3A, so that the welding current at the left end of the arc oscillation is as shown in FIG. 4A, the welding voltage becomes larger as shown in FIG. 6B.
It becomes smaller as compared with (b). Also, in the displacement state shown in FIG. 5 (a), the right end of the arc swing has a protruding length of FIG. 3 (a).
6A, the welding current is smaller than that of FIG. 4A as shown in FIG. 6A, and the welding voltage is opposite to that of FIG. 4B as shown in FIG. 6B. It will be larger than that. Therefore, if the arc oscillating center is controlled so that the waveform of the welding current or the welding voltage accompanying the oscillating movement of the arc 7 is the same on the left and right sides in the narrow groove 4, the right and left position can be copied.

However, as shown in FIG. 1, the wire oscillator 11 for deforming the welding wire 6 in a wave shape and the arc 7 are separated via the welding torch 1 and the welding current waveform detected by the current detector 14 and the arc 7 Synchronizing the swing position is not easy. Therefore, in this embodiment, the arc swing position and the welding current waveform are synchronized by the following method.

As shown in FIG. 1, the distance between the wire oscillator 11 and the arc 7 is L mm (about 300 mm depending on the length of the welding torch), and the oscillation cycle of the welding wire 6 is Z hertz (0. 5 to 1.5 Hz), the feed speed of the welding wire 6 is Vmm / min (5000 to 9000 mm / min)
Then, the shift cycle number X between the position of the wire oscillator 11 and the swing position of the arc 7 can be roughly calculated by an equation of X = 60 LZ / V. Specifically, L is 300 mm, Z is 1 Hz, and V is 7000 mm.
/ Min, X = 2.6, and the wire oscillator 11
And the swinging position of the arc 7 are shifted by 2.6 periods. This value is an approximate value that does not take into account the bending of the welding wire 6 in the thin tube of the welding torch 1, but the oscillation period of the welding wire 6 is as slow as 0.5 to 1.5 Hertz. An error such that the swinging position is reversed left and right does not occur, but rather the arc swinging is performed later than the estimated value. In other words, by performing the above calculation, the control computer 19 can grasp the increasing / decreasing change tendency of the actually measured welding current value, so that the welding current waveform and the arc swing position can be synchronized. Thus, the center of the arc oscillation center control shaft 8 is controlled such that the difference between the waveform integrated values of the welding current or the welding voltage in the right half cycle and the left half cycle of the arc oscillation is always constant, and the right and left position is traced. be able to.

The actual control flow will be described. The control computer 19 previously stores values of the distance L between the wire oscillator 11 and the arc 7, the swing cycle Z of the welding wire 6, and the feed speed V of the welding wire 6. By inputting and calculating the shift cycle number X between the position of the wire oscillator 11 and the swing position of the arc 7 by the above-described equation (X = 60 LZ / V), the swing of the arc 7 from the position of the wire oscillator 11 is calculated. Estimate the moving position. Based on this estimation, the DC amplifier 17 and A
The welding current signal and the welding voltage signal taken into the control computer 19 via the / D converter 18 are synchronized with the arc swing position, so that the welding current or welding voltage of the right half cycle and the left half cycle of the arc swing is synchronized. Then, the arc swing center control shaft 8 on the welding head 15 is controlled so as to follow the left and right position so that the difference between the left and right waveform integrated values is always constant. The estimation of the swing position of the arc 7 based on the above equation may be basically performed once at the start of welding. However, if it is performed periodically to confirm synchronization, more accurate left and right position scanning can be performed. it can.

Next, regarding the swing width control of the arc oscillation,
This will be described with reference to FIGS. FIG. 5B shows a state in which the welding torch 1 is raised above the normal position in the narrow groove 4 and the arc swing width is too large. FIGS. 6C and 6D show welding in this state. The current and welding voltage are shown. When the swing width of the arc is too large, the left and right walls of the narrow groove 4 are excessively melted, which causes an undercut defect. On the other hand, FIG. 5C shows a state in which the welding torch 1 is lowered from a normal position in the narrow groove 4 and the arc swing width is too small, and FIGS. 6E and 6F show this state. 3 shows a welding current and a welding voltage. When the swing width of the arc is too small in this way, the melting of the left and right walls of the narrow groove 4 does not progress and causes a fusion failure. That is, when the welding torch 1 is raised and the arc swing width is increased, the numerical value of the welding current is reduced as a whole, but the difference between the maximum and the minimum is increased, and the welding voltage is increased as a whole and the difference between the maximum and the minimum is also increased. Increase. Also, when the welding torch 1 is lowered and the arc swing width is reduced, the welding current is generally increased in value, but the difference between the maximum and the minimum is reduced, and the welding voltage is reduced as a whole and the difference between the maximum and the minimum is also reduced. to shrink. Since such a phenomenon occurs due to the height of the welding torch 1 in the narrow groove 4, the average value of the welding current or the welding voltage in one cycle of the arc oscillation coincides with the average value in a normal case set in advance. As described above, by correcting the height of the welding torch 1, swing width control for keeping the swing width of the arc 7 constant becomes possible.

More specifically, the average value of the welding current or welding voltage for one cycle of the normal arc oscillation is input to the control computer 19 as a set value. Then, the control computer 1 is connected via the DC amplifier 17 and the A / D converter 18.
An average value of the welding current or welding voltage for one cycle of arc oscillation is obtained based on the welding current signal or welding voltage signal taken in 9, and the average value is compared with the set value to make the difference between them zero. As described above, by controlling the torch height control shaft 9 mounted on the welding head 15, control for keeping the arc swing width constant can be performed.

The above-described groove tracing control of the center of the arc oscillation and the constant control of the width of the arc oscillation allow the wavy wire type narrow groove G to be formed.
Although the automatic operation of the MA welding device becomes possible, when the GMA welding is actually performed continuously for a long time, the wear of the power supply tip 2 provided at the tip of the welding torch 1 progresses. The power supply chip 2 needs to be replaced at an appropriate time. In addition, if the wire oscillator 11 fails during the operation and the welding wire 6 cannot be given a wavy deformation, a large amount of labor is required to repair only the narrow groove welding. Therefore, conventionally, as described above, the operator (operator) had to periodically monitor the arc oscillation state, but in the present embodiment, it is possible to automatically detect an abnormality in the arc oscillation amplitude. Therefore, the operator's monitoring work as in the past can be omitted. Hereinafter, this point will be described in detail with reference to FIGS. 3 and 4 and FIGS. However, FIG. 7 is a structural diagram of the lower block of the welding torch.
(A) is a sectional view, and (b) is a front view. FIG. 8 is a structural view of the power supply chip, and (a) and (c) are cross-sectional views.
(B), (d) is a front view.

As shown in FIGS. 7 and 8, a power supply tip 2 is attached to the lower block 22 of the welding torch 1 having a shield gas passage 23 and a cooling water passage 24 by a screw structure. The power supply tip 2 is provided with a power supply tip hole 25 through which the welding wire 6 is inserted. As shown in the cross-sectional view of FIG. 8A and the front view of FIG. 8B, in the normal power supply chip 2, the power supply chip hole 25 is not worn.
As shown in the sectional view of (c) and the front view of (d), the power supply tip hole 25 has become larger due to wear. If welding is continued while using the feed tip 2 that has been worn in this way, the width of the arc swing becomes too large and the left and right walls of the narrow groove 4 are too melted as shown in FIG. , Undercut occurs. Therefore, when the wear of the power supply tip 2 progresses, the welding must be interrupted and replaced with a new power supply tip 2. When the wire oscillator 11 breaks down and the welding wire 6 cannot be given a wavy deformation, as shown in FIG. 3C, the arc swing stops and normal welding cannot be performed, and the welding is continued as it is. If it has, an extremely complicated rework is required. Specifically, if only the bead surface needs to be cut, a thin bladed disk-shaped grinder may be inserted into the narrow groove 4 to grind the defective bead, but if it is not sufficient to grind only the bead surface, After all defective parts are removed by gouging, they must be re-installed by manual welding.

The abnormality detection of the swing width of the arc in this embodiment is performed as follows. Now, as shown in FIG. 3 (b), the welding torch 1 is in a normal position in the narrow groove 4, but if the power swinging tip 2 is worn and the arc swing width is increased, the welding current waveform and Fig. 4 shows the welding voltage waveform.
(C) and (d) are obtained. That is, when the state shown in FIG. 3B is compared with the normal state shown in FIG. 3A, there is no change in the protruding length of the welding wire 6 from the power supply tip 2 at the arc oscillation center, and thus the arc oscillation is performed. The welding current at the center is equal as shown in FIGS. 4 (a) and 4 (c). However, at the left and right ends of the arc oscillation, in the case of FIG. 3B, the protruding length of the welding wire 6 is shorter than in the normal state, and therefore, as shown in FIGS. The welding current at both ends is larger than normal, and the welding voltage is smaller than normal. Therefore, FIG.
In the state shown in (b), the difference between the maximum value and the minimum value of the welding current and the welding voltage increases as compared with the normal state. Further, when the wire oscillator 11 fails and the welding wire 6 cannot be given a wavy deformation, the arc swing stops as shown in FIG. 3C, and the welding current and welding voltage are changed as shown in FIG. e), it becomes a constant value as shown in (f).

As described above, when the swing width of the arc swing is abnormal, a remarkable change occurs in the welding current and the welding voltage. Therefore, in this embodiment, when the swing position of the arc 7 is in the predetermined area on the right side. Is the difference between the average welding current value or average welding voltage value and the average welding current value or average welding voltage value when the oscillating position is in the center predetermined region, and the oscillating position of the arc 7 is the left predetermined value. The difference between the average welding current value or average welding voltage value when in the region and the average welding current value or average welding voltage value when the swinging position is in the center predetermined region is defined as SL, and the average value of these SR and SL Is out of the range set in advance, it is determined that the swing width of the arc 7 is abnormal. Here, the reason why the average value of the predetermined region of the arc swing position is adopted is to reduce the measurement error, and there is no clear standard of how much the predetermined region should be, but the average value within a narrow range is used. It goes without saying that the sensitivity is increased by adopting. Further, the arc swing position can be estimated by the above-described method in a state where the left and right position scanning of the arc swing center and the constant torch height scanning are performed.

More specifically, the control computer 19
The normal range of the welding current difference or the normal range of the welding voltage difference between the left and right ends and the center of the arc oscillation is input. Then, based on the welding current signal or welding voltage signal taken into the control computer 19 via the DC amplifier 17 and the A / D converter 18, the swing position of the arc 7 is determined to be in the right predetermined region and in the center predetermined region. While obtaining the difference SR of the average welding current value or the average welding voltage value at a certain time,
The difference SL between the average welding current value or the average welding voltage value when the swing position of the arc 7 is in the left predetermined region and the center predetermined region is obtained, and the average value of SR and SL is calculated from the normal range. If it is deviated, it is determined that the arc oscillation amplitude is abnormal, and the welding is terminated.
6 is displayed to that effect. As described above, when the power supply tip 2 wears or the wire oscillator 11 breaks down and an abnormality occurs in the swing width of the arc, this can be automatically detected and the welding can be stopped immediately. Therefore, the welding quality can be improved and unmanned welding for a long time can be performed.

It should be noted that an abnormality in the swing width of the arc oscillation can be detected using the minimum welding current value and the maximum welding voltage value as parameters instead of the average welding current value and the average welding voltage value. That is, the difference between the maximum welding current value or the minimum welding voltage value when the oscillating position of the arc 7 is in the right region and the minimum welding current value or the maximum welding voltage value when the oscillating position is in the central region is SR And the difference between the maximum welding current value or the minimum welding voltage value when the swing position of the arc 7 is in the left region and the minimum welding current value or the maximum welding voltage value when the swing position is in the central region. As SL, these SR
When the average value of SL and SL is out of the preset range, it may be determined that the arc swing amplitude is abnormal.

[0030]

The present invention is embodied in the form described above and has the following effects.

By comparing the difference between the welding current value and the difference between the welding voltage value when the arc oscillating position is in the left and right regions and the central region with the reference value, the arc oscillating amplitude is abnormal. It is possible to automatically determine whether or not the power supply chip has occurred, so that it is possible to quickly and automatically detect the progress of wear of the power supply tip and the occurrence of a failure in the wire oscillator. In other words, the power supply tip can be replaced at an appropriate time without the need for the operator (operator) to monitor regularly or continuously, and the troublesome reworking that may be caused when the welding failure is continued can be avoided. . Therefore, unmanned welding can be performed for a long time, thereby saving labor and increasing efficiency, and improving welding quality.

[Brief description of the drawings]

FIG. 1 is a corrugated wire type narrow groove GMA according to an embodiment of the present invention.
It is a whole block diagram of a welding device.

FIG. 2 is a schematic diagram of a control system for detecting an arc oscillation swing width abnormality in the welding apparatus.

FIG. 3 is a schematic diagram showing an arc swinging state in a narrow groove in a corrugated wire type narrow groove GMA welding.

FIG. 4 is a waveform diagram of welding current and welding voltage corresponding to FIG.

FIG. 5 is a schematic diagram showing an arc swing state when a welding torch is displaced within a narrow groove.

FIG. 6 is a waveform diagram of welding current and welding voltage corresponding to FIG.

FIG. 7 is a structural diagram of a lower block of the welding torch.

FIG. 8 is a structural diagram of a power supply chip.

FIG. 9 is an overall configuration diagram of a corrugated wire type narrow groove GMA welding apparatus for explaining a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Welding torch 2 Power supply tip 3 Base material 4 Narrow groove 6 Welding wire 7 Arc 8 Arc swing center control axis 9 Torch height control axis 10 Wire swing control axis 11 Wire oscillator 12 Control device 14 Current detector 16 Wire feed Supply roller 19 Control computer 25 Power supply tip hole 26 Oscillation swing width abnormal display

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B23K 9/12 310 B23K 9/12 310A 9/173 9/173 D

Claims (2)

[Claims] An arc oscillation is performed by a wave-shaped narrow groove GMA welding in which a wire oscillator gives a large amplitude corrugated plastic deformation to a welding wire and the deformation causes the arc to rock with a large amplitude in a groove wall direction. In the state where the center right and left position scanning and the torch height constant scanning are performed, the average welding current value or the average welding voltage value when the arc swing position is in the right predetermined region and the swing position is in the center predetermined region. The difference between the average welding current value or the average welding voltage value at a certain time is defined as SR, and the average welding current value or the average welding voltage value when the swing position of the arc is in the left predetermined region and the swing position are at the center. The difference between the average welding current value or the average welding voltage value when in the predetermined area is SL, and these SR and S
An arc fluctuation amplitude detection method for narrow groove GMA welding, characterized in that when the average value of L is out of a preset range, it is determined as an arc fluctuation amplitude error. 2. A wave-shaped narrow groove GMA welding method in which a wire oscillator applies a large amplitude corrugated plastic deformation to a welding wire, and the deformation causes the arc to rock with a large amplitude in a groove wall direction. The maximum welding current value or minimum welding voltage value when the swing position of the arc is in the right region, and the swing position is in the center region in the state where the center right and left position scanning and the torch height constant scanning are performed. Is the difference between the minimum welding current value or the maximum welding voltage value and the maximum welding current value or the minimum welding voltage value when the swing position of the arc is in the left region, and the swing position is in the center region. When the difference between the minimum welding current value or the maximum welding voltage value at that time is SL and the average value of SR and SL is out of a preset range, it is determined that the arc swing amplitude is abnormal. A method for detecting an abnormal swing width of an arc in narrow groove GMA welding.