JP3279082B2 - Method and apparatus for detecting position of welding wire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for generating an arc in a welding torch using a non-consumable electrode and performing automatic welding while feeding a welding wire during the arc.
The present invention relates to a detection method suitable for determining whether or not a position of a wire melted in an arc is good and for determining an abnormality of an electrode.

[0002]

2. Description of the Related Art Generally, TIG arc welding and plasma arc welding are known as welding methods using non-consumable electrodes mainly composed of dangsten. In these arc weldings, welding of a joint base metal having a groove or mere overlay welding of a base metal surface is performed by using a welding wire (an arc) generated between an electrode of a welding torch and a welding base metal. Welding is performed while feeding and melting a filler material or wire. However, the position of the welding wire fed into the arc is not always constant, and is extremely affected by the effects of thermal deformation of the welding base material, changes in the arc length, and bending of the wire, in addition to the speed of the wire feed speed. Easy to fluctuate. For this reason, there is a problem that the molten state of the wire is likely to be unstable, and the weld bead is disturbed to deteriorate the welding result. Also, in TIG welding where the electrode is exposed, if the welding wire is too close to the electrode during welding, the electrode is significantly damaged and the arc is disturbed, and on the contrary, the welding wire sticks too much into the welding base material side In addition, there is a problem that the molten pool is disturbed or adhered to, resulting in welding troubles and welding defects. These problems are major obstacles in automating welding and improving welding quality.

[0003] In order to solve such a problem, several methods have been conventionally attempted. For example,
As disclosed in the automatic arc welding method of Japanese Patent No. 4817, a guide tip (wire guide) of a filler material is brought into pressure contact with a welding base material so that a gap between the filler material and the welding base material is fixed. Holding.

On the other hand, although the purpose of use is different, as a method of keeping the arc length constant, a method of detecting an arc voltage (welding voltage) and performing feedback control has been conventionally known. In hot wire TIG welding, in which electric current is applied to a welding wire fed during an arc, in addition to control of the arc length, a means for preventing the disturbance of the arc due to energization of the wire has been proposed. For example, in Japanese Patent Publication No. 5-75511,
A device is disclosed in which a pulse current is used to energize a wire, a wire terminal voltage is detected during a period when the wire is not energized, and the next pulse current is prohibited when the wire and the base material are not in contact.

[0005]

In order to obtain a stable welding transition of the welding wire fed into the arc, obtain a good welding result in the shape of the welding bead, and prevent abnormal wear of the electrode, the quality of the wire position must be determined. It is necessary to perform appropriate position control and electrode abnormality determination.

[0006] However, for example, the automatic arc welding method disclosed in Japanese Patent Publication No. 53-4817 can maintain the height of the welding wire constant irrespective of the variation of the arc length. ) Is not applicable to welding in which the welding torch is swung right and left (weaving) or multilayer multi-pass welding with uneven bead shape because the guide tip (wire guide) is pressed against the welding base material. But not
There is a disadvantage that the base material surface of the contact portion and the guide chip are easily damaged.

[0007] On the other hand, the method of detecting the arc voltage and performing feedback control is effective for constant control of the arc length, but the position of the welding wire fed during the arc is limited.
It is in a completely uncontrolled state, and the occurrence of the above-mentioned trouble of the welding wire cannot be eliminated. Further, for example, a hot wire TIG disclosed in Japanese Patent Publication No. 5-75511
The welding device is effective in preventing arc disturbance due to wire energization, but is ineffective for ordinary welding in which electric current is not applied to the welding wire, and the height control of the wire position is not performed at all. Therefore, it is impossible to manage and control the molten state of the welding wire. In addition, there is no description of any electrode abnormality determination.

SUMMARY OF THE INVENTION It is an object of the present invention to determine whether the position of a wire is good or bad in order to stabilize the melting transfer of a welding wire fed into an arc, obtain a good welding result in a weld bead shape, and prevent abnormal wear of an electrode. It is an object of the present invention to provide a detection method suitable for performing a control command and determining an abnormality of an electrode.

[0009]

An object of the present invention is to provide a welded joint.
Apply current between the base metal and the non-consumable electrode on the tip of the welding torch.
To generate an arc with an arbitrary output waveform,
Welding while feeding non-energized welding wire into the molten pool
In the method for detecting the position of a welding wire when performing
Wire voltage generated between energized welding wire and welding base metal
Wire voltage detecting means for detecting a signal, and the welding wire
And the number of short circuit transitions per unit time when
A wire short-circuit detecting means for determining a short-circuit transition time ratio;
Taking the number of times of transfer and
And wire position determining means for determining the position of the wire.
During the welding period after the occurrence of the
Therefore, the appropriateness or inappropriateness of the height of the wire position is determined,
If the wire position is determined to be inappropriate due to excessive
A control signal to lower the position
If it is determined that the position is too small and inappropriate, raise the height position.
Control signal to raise the
Electrode voltage signal Ve generated between the contact wire and the non-consumable electrode
Electrode voltage detecting means for detecting the welding current,
Detecting welding voltage signal Ea generated between electrode and base material
Judgment of welding voltage detection means and abnormality of electrode and welding wire
Abnormality determining means for determining the position of the wire.
A control signal is issued at the same time as the
After the contact, the electrode voltage signal Ve and the welding voltage signal
Ea is taken into the abnormality determination means, and
The reference voltage value e2 is compared with a reference voltage value e2 for abnormality determination.
2 when the electrode voltage signal Ve is Ve ≦ e2
It is determined that the droplet of the welding wire has contacted the electrode,
When the voltage signal Ea satisfies Ea ≦ e2, the electrode moves to the molten pool.
Judgment of contact and display of welding stop command and electrode abnormality
This is achieved by issuing a command.

[0010] The above object is also achieved by welding a base metal of a welded joint.
Arbitrary output by energizing between the non-consumable electrode of the torch tip
Generates a corrugated arc, in the arc and in the molten pool
When welding while feeding a non-energized welding wire to
In the wire position detecting device, the non-energized welding wire may be used.
Wire voltage signal generated between the wire and the welding base metal
Wire voltage detecting means and short-circuiting of the welding wire
Number of short circuit transitions per unit time and short circuit transition time ratio
Wire short-circuit detecting means for determining
From the output of the step, the quality of the position of the welding wire is determined,
When the wire position is determined to be inappropriate due to excessive wire position, its height
A control signal for lowering the position is generated.
If the position is too small to be judged inappropriate, raise the height position
Wire position determining means for generating a control signal to cause
Electrode voltage generated between non-conductive welding wire and non-consumable electrode
An electrode voltage detecting means for detecting a pressure signal and a welding current flow
A welding voltage signal generated between the electrode and the base material.
Welding voltage detecting means, the electrode voltage signal and the welding voltage.
Takes a signal and sets a preset reference voltage for abnormality determination
The value is compared with the value to judge whether or not it is abnormal.
And an abnormality determining means for issuing a display command of electrode abnormality are provided.
This is achieved by:

[0011]

As described above, by providing the wire position determining means for determining the welding wire position from the number of times of short-circuit transfer per unit time of the welding wire and the short-circuit transfer time rate determined by the wire short-circuit detecting means, the welding wire height is increased. Can be determined as appropriate or inappropriate. In this determination, when the short circuit transition time rate At is At <a (%), or when the short circuit transition time rate At is At <a (%), and the number N of short circuit transitions is N <m (number / second) In the case of, it is determined that the welding wire position height is excessive and inappropriate, and conversely, when the short circuit transition time rate At is At> b, or when the short circuit transition time rate At is At> b, and the number N of short circuit transitions is N When <m, the position of the welding wire is determined to be too small and inappropriate.
When a ≦ At ≦ b and N ≧ m, the welding wire position height is determined to be appropriate. Further, when it is determined from the result of this determination that the wire position is inappropriate, a control signal is transmitted in a direction in which the wire position height is corrected, so that appropriate control of the wire position height can be performed. In addition, by providing abnormality determination means for determining abnormality of the electrode and the welding wire from the electrode voltage signal and the welding voltage signal, it is possible to detect when the welding wire being melted contacts the electrode or when the electrode contacts the molten pool. It can be clearly distinguished. In such a case, a command to stop welding and a command to display an electrode abnormality are issued.
Deterioration of welding results and generation of welding defects can be prevented beforehand.

Further, by using a welding control device and an automatic welding system provided with a function of detecting a position of a welding wire, various welding joints such as welding assemblies of general welding structures, welding pipes, chemical plants and nuclear power plants can be obtained. Pass welding or multilayer multi-pass welding can be performed satisfactorily, and it is possible to automate welding and improve welding quality.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to embodiments. FIG. 1 shows an embodiment of the present invention, which is provided with functions for judging pass / fail of a welding wire melted in an arc, performing position control, and judging an abnormality of an electrode. The object to be welded to the base material 27 is, for example, an example of a welded joint of various pipes required for welding and assembling a chemical plant or a nuclear power plant. Reference numeral 1 denotes a welding torch using a non-consumable electrode 2 containing tungsten as a main component, and is provided via a torch holder 3 on a torch drive shaft 4 that can be driven vertically. 6 is the base material 2 of the electrode 2 and the pipe welding joint of the material to be welded.
The arc 6 is generated between the welding power source 7
As a result, a current waveform of an arbitrary size such as a DC arc or a pulse arc is output. Reference numeral 8 denotes an arc 2 from a welding wire feeding device (omitted) through a wire guide 9.
The welding wire sent inside is provided via a wire holder 10 to a wire drive shaft 20 installed on a torch vertical drive shaft 4 capable of driving vertically. No electrical heating was performed on this welding wire. The base material 27 of the pipe welding joint is provided with a groove having an arbitrary shape.
And is welded while filling the groove with the molten metal of the welding wire 8. In the case of a thin plate with a small groove, one-pass welding is performed, and in the case of a thick plate with a large groove, multi-pass welding is performed.
Numeral 28 is a pipe traveling carriage capable of traveling at an arbitrary set speed on the traveling rail 12 installed along the welding line of the base material 27 of the pipe welding joint, and is a vertical carriage of the welding torch and the welding wire. A torch drive shaft 4 that can be driven simultaneously is mounted. 21 is a welding torch 1 and a welding wire 8
This is a torch left / right drive shaft capable of controlling left / right movement and swing of the torch. Reference numeral 20 denotes a wire drive shaft capable of controlling drive of the welding wire 8 in the up-down and left-right directions. The wire drive shaft 20 is provided on the torch left-right drive shaft 21 so that the positioning of the welding wire 8 can be performed independently. ing. further,
Reference numeral 13 denotes a wire voltage detecting means for detecting a wire voltage signal Vw generated between the non-energized welding wire 8 and the base material 27 of the welding joint. Numeral 14 denotes a wire short-circuit detecting means for detecting a short-circuit transition of the welding wire 8, which takes in the wire voltage signal Vw from the wire voltage detecting means 13 and compares it with a reference voltage e1 of the wire short-circuit. The number of transitions and the short-circuit transition time ratio are detected and calculated. Reference numeral 15 denotes welding wire position determining means for determining the position of the welding wire. The welding wire position determining means 14 determines the quality of the welding wire position based on the number of times of short circuit transfer and the short circuit transfer time rate obtained by the wire short circuit detecting means 14. When the position of the welding wire is determined to be too small or too large by the welding wire position determining means 15, a control signal for correcting the position of the wire is transmitted to the welding controller 16. . The torch drive shaft 4 is driven and controlled by a control signal transmitted from the welding wire position determination circuit 15 to the welding controller 16. Further, reference numeral 23 denotes an electrode voltage detecting means for detecting an electrode voltage signal 22 of a voltage Ve generated between the non-energized welding wire 8 sent into the arc 2 and the electrode 2 where the arc 2 is generated. Is a welding voltage detecting means for detecting a welding voltage signal 25 of a voltage Ea generated between the electrode 2 where the arc 2 is generated and the base material 5. Also,
Reference numeral 24 denotes abnormality determining means for determining abnormality of the welding wire and the electrode. The electrode voltage detecting means 23 and the welding voltage detecting means 26
Voltage signal Ve and welding voltage signal Ea transmitted from
Is compared with a reference voltage e2 for abnormality determination to determine the presence or absence of an abnormality. When it is determined by the abnormality determination circuit 24 that there is an abnormality, a welding stop command and a display command of an electrode abnormality are transmitted to the welding controller 16. The welding controller 16 includes, in addition to the drive control of each of the torch drive shaft 4, the torch left and right drive shaft 21 and the wire drive shaft 20, the travel control of the traveling vehicle 28, the output control of the welding power source 7, and the welding wire feeding. Each control circuit or control means capable of performing a series of controls necessary for welding, such as control of equipment (omitted), is stored (omitted). Reference numeral 17 denotes a storage device that stores the wire short-circuit detection circuit 14, the welding wire position determination circuit 15, and the welding controller 16.

Next, the melting characteristics of the welding wire and a method for determining the position of the wire based on the melting characteristics will be described. As shown in FIG. 2, when a non-conductive welding wire 8 is sent into an arc 6 generated between the electrode 2 and the base material 5 of the material to be welded, a voltage Vw is applied between the welding wire 8 and the base material 5. As a result, the wire-base metal voltage Vw changes depending on the state of melting of the welding wire 8 and the transfer of the droplet. For example, FIG. 3 is a typical waveform example of the voltage Vw between the wire and the base material observed when the arc length L or the distance between the wire and the base material is changed. A short-circuit condition that remains in contact with the molten pool,
(B) shows a state in which droplets sometimes transfer from a short circuit, (c) shows a state in which fine droplets repeatedly transfer to a short circuit in a short time, and (d) shows a state in which droplets that have grown large sometimes transition. . With respect to the reference voltage e1 of the wire short-circuit,
Each time ts in the region where the base metal voltage Vw satisfies Vw ≦ e1 is where a wire short circuit occurs. Therefore, a wire-base metal voltage Vw at which a potential difference occurs when the wire droplet is transferred.
The number N of short-circuit transitions of the wire droplet and the short-circuit transition time ratio At can be obtained from the waveforms of the above. That is, the detection time is T
(sec) and the number of short circuits is n (times), the number of short circuit transitions per unit time N (times / sec) is N = n / T, and the short circuit transition time ratio At (%) at that time is At = (Σt
s / T) × 100.

FIG. 4 shows the relationship between the arc length L (distance between the electrode and the base material) and the number N of times the wire droplet is shifted to a short circuit when welding is performed using a DC arc and a pulse arc, respectively. According to the present experiment, the number of transitions of the wire droplet to the short circuit N
When the arc length L is short (the distance between the wire and the base material is also short), the contact time between the base material and the molten pool is long, so that the number of times is small. After that, the arc length is long (wire
As the distance between the base materials becomes longer, the droplets grow and move as they move, so that they again decrease. This tendency is observed in both DC arc and pulse arc. FIG.
As shown in FIG. 4 and FIG. 4, when the arc length L and the distance between the wire and the base material are too short (a), the molten pool tends to be unstable, and the formation of a weld bead tends to be extremely deteriorated. In particular, in the weaving welding in which the welding torch and the wire are swung right and left, troubles such as the adhesion of the wire to the base material or the interruption of the welding due to contact with the electrode tend to occur frequently. Further, in the state of (d) where the arc length L or the distance between the wire and the base material is too long, the arc and the weld bead are disturbed by the transfer of a large grown unstable wire droplet, so that a welding defect is easily generated. In contrast, (b)
In the states (c) and (c), it was found that the transfer of the droplet of the wire and the arc were stable, and a good welding result of the weld bead was obtained. Therefore, in order to maintain the stable regions of (b) and (c), the reference value m for the number of short circuit transitions is provided, and the wire position height is set so that the number N of short circuit transitions during welding always becomes N ≧ m. Is controlled. The criterion value for the number of short circuit transitions may be about m = 3 to 5 (number / sec), and the wire position height is controlled by controlling the torch drive shaft on which the welding torch 1 and the welding wire 8 are mounted. Can be achieved by doing However, it is difficult to distinguish whether the wire position height is too small or too large when N <m by only the determination of the number of times of short circuit transfer.
By utilizing the characteristics of the short-circuit transition time ratio of the wire droplet, it is possible to determine the classification. FIG. 5 shows the relationship between the arc length and the rate of transition of the wire droplet to the short circuit. FIG. 5 shows the results obtained by changing the current value of the pulse arc into three types, large, medium, and small. The wire drop short circuit transition time ratio At rapidly decreases from 100% in the short circuit area as the arc length L and the distance between the wire and the base material increase, and then becomes 0.
%. With respect to the upper limit reference value b of the short-circuit transition time ratio, the short-circuit transition time ratio At is greater than At> b.
In this case, the wire position height is too small, resulting in an unstable region. In addition, with respect to the lower limit reference value a of the short circuit transfer time ratio, At <a
In the case of, the height of the wire position is excessively large, resulting in an unstable region. It can be seen that the stable region of the wire droplet and welding is a region excluding these unstable regions, and is a region satisfying a ≦ At ≦ b. The lower limit reference value of the short circuit transfer time ratio is about a =
5 to 20 (%), and the upper limit reference value is about b = 80 to 99.
(%).

Therefore, the number N of short-circuiting transitions of the wire droplet and the short-circuiting transition time ratio At are determined by the wire short-circuit detecting means 14 shown in FIG. 1, and this information is taken into the welding wire position determining means 15 to determine whether the wire position is good or bad. The judgment is made. For example, if the short-circuit transition time ratio At is At <
a, or the number N of short circuit transitions is N <m, and
When At <a, it is determined that the wire position height is excessive, and a control signal of descending is transmitted to the welding controller 16. Further, when the short-circuit shift time ratio At is a ≦ At ≦ b or when the number N of short-circuit shifts is N ≧ m, it is determined that the wire position height is appropriate and the wire position height is maintained as it is. ing. Conversely, when At> b, or N <m, and At> b, the height of the wire position is determined to be too small, and a control signal for ascending is transmitted to the welding controller 16. When the welding controller 16 receives a descending control signal from the wire position determining circuit 15, the welding torch 1 and the torch drive shaft 4 on which the welding wire 8 is mounted are controlled to descend.
Conversely, when the ascending control signal is received, the torch drive shaft 4
Is controlled in the ascending direction. When the wire position height is appropriate and no vertical movement control signal is output, the control is performed so that the heights of the welding torch and the welding wire are maintained as they are. When the torch drive shaft 4 is provided with an operation for controlling the arc length to be constant, the torch drive shaft 4 is controlled in the ascending direction or the descending direction by the wire position determination circuit 15 to determine whether the wire position is good or not. At this time, the control operation for keeping the arc length constant for the control period may be stopped so that the control instruction of the wire position determination circuit is made to follow. Further, when the wire position height is determined to be appropriate by the wire position determination circuit 15, the arc length constant control operation may be restarted so as to maintain the wire position height, and the torch drive shaft may be continuously controlled. . In this way, by controlling the welding torch and the torch drive shaft on which the welding wire is mounted, appropriate control of the wire position height can be performed. Transfer of wire droplets and good welding results can be obtained.

A method of diagnosing abnormalities of the welding wire and the electrode will be described. 6 and 7 show the welding voltage Ea during welding.
And an example of a signal waveform of the electrode voltage Ve, where ts in the figure is a short-circuit transition time of the wire droplet, and ta
Represents the contact time of the electrode. As can be seen from a comparison with the signal waveform of the wire voltage Vw shown in FIG. 3, when the wire droplet shifts to a short circuit (short circuit shift time ts), the level of the wire voltage Vw decreases to near 0 V.
The electrode voltage Ve has such a characteristic that it almost rises to the level of the welding voltage only during the short circuit transition time ts. FIG.
The point of ta where the level of the electrode voltage Ve is reduced to near 0 V is when the disturbed droplet of the welding wire comes into contact with the electrode. Since the arc 2 is generated as it is, the welding voltage slightly changes. It shows how to do. On the other hand, when the electrode 2 and the welding wire 8 come into contact with the molten pool of the base materials 5 and 27 (contact time ta), the levels of the welding voltage signal Ea and the electrode voltage signal Ve decrease to near 0 V as shown in FIG. I do. When such a contact phenomenon occurs, not only is the electrode damaged and abnormally worn out, but if welding is continued as it is, it becomes difficult to continue normal arcing and welding defects occur.

Therefore, in order to prevent this, here, a reference voltage e2 for contact determination is provided, and the levels of the welding voltage Ea and the electrode voltage Ve are monitored by the abnormality determining means 24. During the welding period, when the welding voltage signal Ea satisfies Ea ≦ e2, it is determined that the electrode has contacted the molten pool. When the electrode voltage signal Ve satisfies Ve ≦ e2, the droplet of the welding wire has contacted the electrode. And a command to stop welding and a command to display an electrode abnormality are transmitted to the welding controller 16. Reference voltage e for contact determination
2 is preferably set to be larger than 0 and about 3 V or less in consideration of contact resistance and cable resistance. With this configuration, wear due to electrode contact can be minimized, and occurrence of welding defects and deterioration of welding quality due to troubles in the welding wire and electrode can be prevented.

FIGS. 8 and 9 show one embodiment of a control operation flowchart of the present invention. Such a control operation can be created by software and incorporated in the welding control storage device 17, for example. First, after the arc ON31 where the arc is generated and the welding wire are fed, the wire feed ON3 is turned on.
The detection is started after the second detection waiting time 33. After performing the wire position detection and control processing 35, an electrode abnormality detection processing 36 is performed, and the processing operation is repeated until the arc is turned off 37 (welding is completed). In the electrode abnormality detection process 36, an electrode base material contact detection 37 and a wire electrode contact detection 38 are performed. When the level of the welding voltage signal Ea satisfies Ea ≦ e2, it is determined that the electrode has contacted the molten pool (base metal contact 40). When the level of the electrode voltage signal Ve satisfies Ve ≦ e2, It is determined that the droplet of the welding wire has come into contact with the electrode (wire contact 42), and the stop 43 of the welding and the abnormality display 44 of the electrode are performed. On the other hand, wire position detection and control processing 35
In FIG. 12, as shown in FIG. 12, the number of short circuit transitions N (49) and the number of short circuit transitions occurring during the sampling time T (46) of the detection 45 of the wire base metal voltage Vw 45 set separately for the DC arc 47 and the pulse arc 48 After the time rate At (50) is obtained, the quality determination of the wire position height is performed from the result determination. Here, for example, the number N of short-circuit shifts is N
≧ m, N <m, and the short circuit transition time ratio At is a
When ≤At≤b, the wire position height is appropriate 51,52
And the wire position height is maintained as it is 53
It is controlled to be. Also, if N <m and At <
In the case of a, the wire position height is determined to be excessive 54, and the wire drive shaft lowering control 56 is moved in the direction of lowering only the welding wire in accordance with the cumulative value of wire lowering (Σ △ Vn ≦ c1).
Or the lowering control 57 of the torch drive shaft is performed in the direction of lowering both the welding torch and the welding wire. On the other hand, when N <m and At> b, the wire position height is determined to be too small 58, and both the welding torch and the welding wire are raised in accordance with the cumulative value of the torch rise (Σ △ Z ≦ c2). Then, the torch drive shaft raising control 60 is performed, or the wire driving shaft raising control 61 is performed in a direction to raise only the welding wire. Note that the lower limit value c1 of the wire descent may be set to about the initially set arc length L, and the upper limit value c2 of the rise of the welding torch may be set to about twice the initially set arc length L.

With this configuration, the number N of short-circuiting transitions of the wire droplet during welding and the short-circuiting transit time rate At
From this, it is possible to determine the quality of the wire position height. Then, based on the determination result, whether to control the torch drive shaft 4 on which the welding torch 1 and the welding wire 8 are mounted,
Alternatively, by controlling the wire drive shaft 20 that moves only the position of the welding wire 8 up and down, appropriate control of the wire position height can be performed more accurately, without causing disturbance of the wire droplets and failure of the weld bead. It is possible to always obtain stable wire droplet transfer and good welding results. Also,
The provision of the wire drive shaft 20 enables the positioning of the welding wire in the up, down, left, and right directions to be performed independently, so that not only the transfer of the wire droplet can be finely managed, but also the usability can be improved. Furthermore, by diagnosing abnormalities of the welding wire and the electrode, wear due to electrode contact can be minimized, and occurrence of welding defects and deterioration of welding quality due to trouble of the welding wire and the electrode can be prevented.

By equipping the automatic welding system with the function of controlling the position of the welding wire of the present invention, one of various types of welded joints can be obtained.
Appropriate control of the position of the welding wire and abnormality determination of the electrode can be performed for the pass welding and the multi-pass welding, so that the welding can be automated and the welding quality can be improved. For example, it can be applied to automatic welding of chemical plants and nuclear power plants having many welding pipes.

[0022]

By using the method and apparatus for detecting the position of a welding wire according to the present invention, it is possible to easily determine the quality of the welding wire position related to the quality of the welding bead shape.
Appropriate control of the wire height becomes possible, and a good welding result of the weld bead can be obtained. In addition, when an abnormality occurs in the electrode and welding wire during welding, the abnormality is instantly detected and the welding is stopped, so that abnormal consumption of the electrode is minimized, and the occurrence of welding defects and welding Deterioration of the result can be prevented. Furthermore, by using the welding control device and the automatic welding system provided with the function of detecting the position of the welding wire of the present invention, one-pass welding of various welded joints such as welded structures of welded structures, welding pipes, chemical plants and nuclear power plants. Alternatively, even for multi-pass multi-pass welding, proper detection of the welding wire position and abnormality diagnosis of the electrodes can be performed, so that even a novice can easily carry out the welding, it is easy to use, and the welding is automated and the welding quality is improved. Improvement can be achieved.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment showing contents related to control of a welding wire position according to the present invention.

FIG. 2 is an explanatory view showing a position of a welding wire sent during the arc of the present invention.

FIG. 3 is a waveform diagram of a typical wire-base metal voltage Vw observed in the wire melting characteristics of the present invention.

FIG. 4 is an explanatory diagram showing a relationship between an arc length and the number of times of short circuit transition of wire melting according to one embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a relationship between an arc length and a short-circuit transition time ratio according to one embodiment of the present invention.

FIG. 6 is a waveform diagram of a representative welding voltage and a voltage between a wire and an electrode, which are determined by the abnormality diagnosis of the welding wire and the electrode according to the present invention.

FIG. 7 is another waveform diagram of a typical welding voltage and a voltage between a wire and an electrode, which are determined by abnormality diagnosis of a welding wire and an electrode according to the present invention.

FIG. 8 is an operation flowchart relating to control of the position of a welding wire and abnormality diagnosis of an electrode according to the present invention.

FIG. 9 is an operation flowchart relating to control of a welding wire position according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... welding torch, 2 ... electrode, 4 ... torch drive shaft, 6 ... arc, 7 ... welding power supply, 8 ... welding wire, 12 ... running rail, 15 ... welding wire positioning means, 16 ... welding controller, 23 ... electrode voltage Detecting means, 24 ... abnormality determining means, 2
7: Base material of pipe welding joint, 28: Pipe welding traveling cart.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuhiko Mizuguchi 3-1-1 Sachimachi, Hitachi-shi, Ibaraki Pref. Hitachi, Ltd. Inside the Hitachi Plant (72) Inventor Yuji Yamaguchi 3-1-1 Sachimachi, Hitachi-shi, Ibaraki No. 1 Hitachi, Ltd. Hitachi Plant (72) Inventor Eiji Hino 3-1-1 Komachi, Hitachi, Ibaraki Pref. Hitachi Plant Hitachi Plant (56) References JP-A-63-26272 (JP, A) JP-A-55-81084 (JP, A) JP-A-62-252679 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 9/127 B23K 9/10 B23K 9 / 167

Claims (2)

(57) [Claims] An electric current is applied between a base material of a welding joint and a non-consumable electrode at the tip of a welding torch to generate an arc having an arbitrary output waveform, and a non-current welding wire is provided in the arc and in a molten pool. A wire voltage detecting means for detecting a wire voltage signal generated between the non-energized welding wire and the welding base metal, and the welding wire is short-circuited. Wire short-circuit detection means for determining the number of short-circuit transitions per unit time and the short-circuit transition time ratio;
A wire position determining means for determining the position of the welding wire by taking in the number of times of short circuit transfer and the ratio of short circuit transfer time, and the height of the wire position is determined by the wire position determining means during a welding period after an arc is generated. The wire position is determined to be inappropriate or inappropriate, and when the wire position is determined to be inappropriate due to excessiveness, a control signal for lowering the height position is generated. An electrode voltage detecting means for generating a control signal for raising the position, and detecting an electrode voltage signal Ve generated between the non-energized welding wire and the non-consumable electrode; and the electrode and the base material through which a welding current flows. a welding voltage detection means for detecting a welding voltage signal Ea occurring between, and an abnormality judging means for judging abnormality of the electrodes and the welding wire is provided, the operation simultaneously with the wire position determining means , Or after sending of the control signals of the wire position height, incorporating the electrode voltage signal Ve and the welding voltage signal Ea to the anomaly determination unit, compared with the reference voltage value e2 of a preset abnormality determination, the Reference
When the electrode voltage signal Ve is Ve ≦ e2 with respect to the pressure value e2,
Sometimes it is determined that the droplets of the welding wire have contacted the electrode,
When the welding voltage signal Ea satisfies Ea ≦ e2, the electrode
Command to stop welding and abnormal electrodes
A method for detecting the position of a welding wire, characterized by issuing a display command . 2. An electric current is applied between the base material of the weld joint and the non-consumable electrode at the tip of the welding torch to generate an arc having an arbitrary output waveform. In a welding wire position detecting device for performing welding while feeding, a wire voltage detecting means for detecting a wire voltage signal generated between the non-energized welding wire and the welding base material, and when the welding wire transitions to a short circuit. Wire short-circuit detection means for determining the number of short-circuit shifts per unit time and the short-circuit shift time ratio;
Whether the position of the welding wire is good or bad is determined from the output of the wire short-circuit detecting means, and when the position of the welding wire is determined to be excessive and inappropriate, a control signal for lowering the height position is generated. A wire position determining means for generating a control signal for raising the height position when determined to be inappropriate, and an electrode voltage detecting means for detecting an electrode voltage signal generated between the non-conductive welding wire and the non-consumable electrode. A welding voltage detecting means for detecting a welding voltage signal generated between the electrode and the base material through which a welding current flows; and a preset reference voltage value for abnormality determination by taking in the electrode voltage signal and the welding voltage signal. To determine if it is abnormal,
A welding wire position detecting device provided with an abnormality discriminating means for issuing a welding stop command and a display command of an electrode error when an error occurs.