JPH081336A - Method and device for detecting welding wire position - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a weld defect, to automate welding, and to improve a welding quality by distinguishing the acceptable or the nonacceptable of a welding wire position and judging the abnormality of an electrode, which affect the acceptable or the nonacceptable of the shape of welding beads. CONSTITUTION:A wire voltage detecting means 13 detecting a wire voltage signal generating between a nonenergized welding wire 8 to be sent into an arc 6 and a welding base material 5 and a wire short circuit detecting means 14 detecting the short circuit transfer of a welding wire, are provided, and a wire position distinguishing means 15 distinguishing a welding wire position is provided. After making a wire position distinguishing means 15 distinguish the properness or the improperness of the height of a welding wire position by fetching the frequency of a short circuit transfer and a short circuit transfer time ratio per unit time, which are found by the wire short circuit detecting means 14 during a welding period, into the wire position distinguishing means, when the height of the welding wire position is excessive and improper, a control signal making its height lower is transmitted, and to the contrary, when the height of the welding wire position is too little and improper, the control signal making its height rise is transmitted respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of performing an automatic welding by generating an arc in a welding torch using a non-consumable electrode and feeding a welding wire into the arc.
The present invention relates to a detection method and apparatus suitable for determining the quality of a position of a wire melted in an arc and determining an abnormality of an electrode.

[0002]

2. Description of the Related Art Generally, TIG arc welding or plasma arc welding is known as a welding method using a non-consumable electrode whose main component is dangsten. In these arc welding, in contrast to welding of a joint base metal with a groove or mere overlay welding of the base metal surface, the welding wire (in the arc generated between the electrode of the welding torch and the welding base metal) Welding is performed while feeding and melting a filler material or wire). However, the position of this welding wire fed into the arc is not always constant, and is extremely affected by the effects of thermal deformation of the welding base metal, changes in the arc length, bending of the wire, etc. in addition to the wire feed speed. It is easy to change. Therefore, there is a problem that the molten state of the wire is likely to be unstable, the welding bead is disturbed, and the welding result is deteriorated. Further, in TIG welding where the electrode is exposed, if the welding wire comes too close to the electrode and comes into contact with the electrode during welding, the electrode will be significantly damaged and the arc will be disturbed, and conversely the welding wire will plunge into the welding base metal side too much. There is a problem that the molten pool is disturbed or adheres to cause welding troubles and welding defects. These problems are major obstacles to automation of welding and improvement of welding quality.

In order to solve such a problem, several methods have been tried in the past. For example, Japanese Patent Publication Sho 53-
As disclosed in the arc automatic welding method of Japanese Patent No. 4817, the guide tip (wire guide) of the filler metal is pressed into contact with the welding base metal to make the gap between the filler metal and the welding base metal constant. keeping.

On the other hand, a method of detecting the arc voltage (welding voltage) and performing feedback control is conventionally known as a method of keeping the arc length constant although the purpose of use is different. Further, in hot wire TIG welding in which the welding wire fed into the arc is energized and heated, a means for preventing the disturbance of the arc due to the energization of the wire has been proposed in addition to the control of the arc length. For example, in Japanese Patent Publication No. 5-75511,
An apparatus 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 with each other.

[0005]

In order to obtain a stable welding transition of the welding wire fed into the arc, obtain a good welding result of the welding bead shape, and prevent abnormal wear of the electrode, it is necessary to judge whether the wire position is good or bad. Therefore, it is necessary to perform appropriate position control and electrode abnormality determination.

However, for example, the automatic arc welding method disclosed in Japanese Patent Publication No. 53-4817 is capable of keeping the height of the welding wire constant regardless of the variation of the arc length. Since the guide tip (wire guide) of) is pressed against the welding base metal, it cannot be applied to welding in which the welding torch is oscillated to the left or right (weaving) or multilayer multi-pass welding with uneven bead shape. Not
There is a drawback that the surface of the base material of the contact portion and the guide tip are easily damaged.

On the other hand, the method of detecting the arc voltage and performing the feedback control is effective for the constant control of the arc length, but the position of the welding wire fed into the arc is
Since it is completely uncontrolled, it is impossible to eliminate the occurrence of welding wire trouble. Furthermore, for example,
The hot wire TIG welding device disclosed in Japanese Patent No. 5511 is effective in preventing the disturbance of the arc due to the electric current flowing through the wire, but is not effective in ordinary welding in which the electric current is not applied to the welding wire. Since the height control of the wire position is not performed at all, the molten state of the welding wire cannot be managed and controlled.

The object of the present invention is to determine whether the wire position is good or bad in order to obtain a stable welding transition of the welding wire fed into the arc, obtain a good welding result of the welding bead shape, and prevent abnormal wear of the electrode. It is an object of the present invention to provide a detection method and apparatus suitable for performing a control command and an electrode abnormality determination.

[0009]

SUMMARY OF THE INVENTION According to the present invention, an arc having an arbitrary output waveform is generated by applying an electric current between a base material of a welded joint and a non-consumable electrode at a tip of a welding torch, and in the arc and in a molten pool. A wire voltage detecting means for detecting a wire voltage signal Vw generated between the non-energized welding wire and the welding base metal by a method of detecting a welding wire position when performing welding while feeding a non-energized welding wire into the inside; A wire short circuit detecting means for detecting a transition of a short circuit of the welding wire is provided, and a wire position judging means for judging a welding wire position is provided so that the wire voltage signal Vw is taken into the wire short circuit detecting means during a welding period after the arc is generated. After comparing with the reference voltage e1 of the wire short circuit, the number N of short circuit transitions per unit time and the short circuit transition time ratio At of the welding wire are obtained, and the number of short circuit transitions and The short circuit transition time ratio is taken into the wire position discriminating means to determine whether the welding wire position is good or bad. If this wire position discriminating means determines that the height of the welding wire position is excessive and inappropriate, the height is lowered. On the contrary, when it is determined that the height of the welding wire position is too small and inappropriate, the control signal for raising the height of the welding wire position is transmitted respectively. .

Another aspect of the present invention is to energize between a base metal of a welded joint and a non-consumable electrode at a tip of a welding torch to generate an arc of arbitrary output waveform, and to generate arc in the arc and in a molten pool. A device for detecting a welding wire position when performing welding while feeding a non-energized welding wire, wire voltage detecting means for detecting a wire voltage signal generated between the non-energized welding wire and the welding base metal, and arc generation During the subsequent welding period, after taking in the wire voltage signal Vw and comparing it with the reference voltage e1 of the wire short circuit to detect the short circuit transition of the welding wire, the number N of short circuit transitions of the welding wire per unit time and the short circuit transition time. A wire short-circuit detecting means for obtaining the rate At is provided, and further, the number of short-circuit transitions and the short-circuit transition time rate obtained by the wire short-circuit detecting means are taken in to determine the quality of the welding wire position. At the same time, when the height of the welding wire position is judged to be too high, a control signal for lowering the height is sent, and conversely, when the height of the welding wire position is judged to be too low, a control signal for raising the height is sent respectively. The welding wire position detecting device is characterized in that a wire position discriminating means is provided.

Still another aspect of the present invention is an electrode for detecting an electrode voltage signal generated between a non-consumable electrode for generating an arc of an arbitrary output waveform and a non-conducting welding wire sent in the arc. A voltage detecting means and a welding voltage detecting means for detecting a welding voltage signal generated between the electrode through which the welding current flows and the welding base metal are provided, and further an abnormality determining means for determining an abnormality of the electrode and the welding wire is provided. During the welding period after the arc is generated, the electrode voltage signal Ve and the welding voltage signal Ea are taken into the abnormality determining means, and the electrode voltage signal Ve is V with respect to the reference voltage value e2 for abnormality determination.
When e ≦ e2, it is determined that the droplet of the welding wire which is being melted has contacted the electrode, and when the welding voltage signal Ea is Ea ≦ e2 with respect to the reference voltage value e2 for abnormality determination, the electrode is in the molten pool. It is determined that the contact has been made with, and a command to stop welding and a command to display the electrode abnormality are issued. Further, the function of detecting the position of the welding wire is provided inside the welding control device so as to operate as an automatic welding system.

[0012]

As described above, by providing the wire position discriminating means for discriminating the position of the welding wire from the number of short circuit transitions per unit time and the short circuit transition time ratio of the welding wire obtained by the wire short circuit detecting means, the welding wire height can be determined. Appropriate
Inappropriate judgment can be performed. In this determination, when the short circuit transition time rate At is At <a (%), or the short circuit transition time rate At is At <a (%), and the short circuit transition number N is N <m (number / second). When the welding wire position height is too large, it is determined that the welding wire position height is not appropriate. On the contrary, when the short circuit transition time ratio At is greater than At> b, or the short circuit transition time ratio At
Is At> b and the number N of short-circuit transitions is N <m, it is determined that the welding wire position height is 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 this determination result that the wire position height is inappropriate, the control signal is transmitted in the direction in which the wire position height is corrected, so that the wire position height can be appropriately controlled.

Further, by providing abnormality determining means for determining abnormality of the electrode and the welding wire from the electrode voltage signal and the welding voltage signal, when the welding wire being melted contacts the electrode or the electrode contacts the molten pool. It is possible to clearly determine that. In such a case, the welding stop command and the electrode abnormality display command are issued, so that it is possible to know the defect of the electrode and the welding wire and at the same time prevent the deterioration of the welding result and the occurrence of welding defects. It becomes possible to do.

Further, by using the welding control device and the automatic welding system provided with the function of detecting the position of the welding wire, it can be applied to various welded joints such as general welding structures, welding pipes, chemical plants and welding assembly of nuclear power plants. The pass welding or the multi-pass multi-pass welding can be carried out favorably, and the welding can be automated and the welding quality can be improved.

[0015]

EXAMPLES The contents of the present invention will be specifically described below with reference to examples. FIG. 1 shows an embodiment of the present invention, in which a welding torch 1 uses a non-consumable electrode 2 containing tungsten as a main component, and a torch holder 3 is mounted on a torch drive shaft 4 which can be driven in the vertical direction. It is provided through. Reference numeral 6 is an arc generated between the electrode 2 and the base material 5 of the material to be welded. The arc 6 is designed so that the welding power source 7 outputs a current waveform of arbitrary size such as a DC arc or a pulse arc. . 8 is a welding wire feeder (omitted)
The welding wire is fed from the wire to the arc 2 through the wire guide 9 and is provided via the wire holder 10 on the torch vertical drive shaft 4 which can be driven in the vertical direction, like the welding torch 1. The welding wire is not electrically heated. The base material 5 of the welded joint is provided with a groove having an arbitrary shape, is heated and melted by the arc 2, and is welded while filling the groove with the molten metal of the welding wire 8. For thin plates with shallow groove, perform 1-pass welding.
When the groove is a deep plate, multi-layer multi-pass welding is performed. Reference numeral 11 is a traveling carriage that can travel on a rail 12 installed along the welding line at an arbitrary set speed, and is equipped with a torch drive shaft 4 capable of simultaneously driving a welding torch and a welding wire in the vertical direction. Has been done. A welding robot that plays this role may be used instead of the traveling carriage 11. Although the torch left and right drive shafts required when weaving welding is performed by swinging the welding torch and the welding wire to the left and right, the torch drive shaft 4 is not shown.
It will be mounted on the traveling vehicle 11 in the same manner as. Reference numeral 13 is a wire voltage detecting means for detecting a wire voltage signal Vw generated between the non-energized welding wire 8 and the base material 5 of the weld joint. Reference numeral 14 is a wire short-circuit detecting means for detecting a short-circuit transition of the welding wire 8. The wire voltage signal Vw from the wire voltage detecting means 13 is fetched and compared with a reference voltage e1 of the wire short-circuit, and then a short circuit per unit time of wire melting. The number of transitions and the short circuit transition time rate are detected and calculated. Reference numeral 15 is a welding wire position discriminating means for discriminating the position of the welding wire. The welding wire position discriminating means 15 discriminates the quality of the welding wire position from the number of short circuit transitions and the short circuit transition time ratio obtained by the wire short circuit detection means 14. When the welding wire position discriminating means 15 discriminates that the position height of the welding wire is too small or too large, a control signal for correcting the wire position height is transmitted to the welding controller 16. . Then, the torch drive shaft 4 is driven and controlled by the control signal transmitted from the welding wire position determination means 15 to the welding controller 16. In addition to the drive control of the torch drive shaft 4, the welding controller 16 includes a traveling control of the traveling carriage 11, an output control of the welding power source 7, a torch left / right drive shaft, and a welding wire feeding device (omitted). Each control circuit or control means (omitted) capable of performing a series of control necessary for welding such as control is stored. Reference numeral 17 denotes a storage device which stores the wire short circuit detection means 14, the welding wire position determination means 15, and the welding controller 16.

Next, the melting characteristic of the welding wire and the method of discriminating the wire position from this characteristic will be described. As shown in FIG. 2, when the non-energized welding wire 8 is sent into the arc 6 generated between the electrode 2 and the base material 5 of the material to be welded, a voltage Vw is generated between the welding wire 8 and the base material 5. And that wire
The base material voltage Vw changes depending on the state of melting of the welding wire 8 and the transfer of droplets. For example, FIG. 3 is a waveform example of a typical wire-base metal voltage Vw observed when the arc length L or the wire-base metal distance is changed.
(1) is a short circuit state in which the wire remains in contact with the base material and the molten pool, (2) is a state in which droplets sometimes shift from the short circuit,
(3) shows a state in which small droplets repeat short-circuit transfer in a short time, and (4) shows a state in which large grown droplets sometimes transfer. The wire short circuit is occurring at each time ts in the region where the wire-base material voltage Vw is Vw ≦ e1 with respect to the wire short circuit reference voltage e1. Therefore, it is possible to determine the number N of short-circuit transitions and the short-circuit transition time ratio At of the wire droplets from the waveform of the voltage Vw between the wire and the base material in which a potential difference occurs during the transfer of the wire droplets. That is,
If 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 (%) is At.
= (Σts / T) × 100.

FIG. 4 shows the relationship between the arc length L (distance between the electrode and the base metal) and the number N of short-circuiting transitions of wire droplets when welding using a DC arc and a pulse arc, respectively. According to this experiment, the number N of times the wire droplet has transferred to the short circuit
When the arc length L is short (the distance between the tire and the base metal is also short), the contact time with the base metal and the molten pool is long, so the number of times is small, and the maximum is the position where the fine droplets migrate in a short time. , Then the arc length is long (
As the distance between the base materials becomes longer), the droplets migrate while growing and show a decrease again. This tendency is observed in both DC arc and pulse arc. FIG.
Also, as shown in FIG. 4, when the arc length L and the distance between the wire and the base metal are too short (1), the molten pool is likely to be unstable, and the formation of weld beads is extremely likely to deteriorate. In particular, in the weaving welding in which the welding torch and the wire are swung left and right, problems often occur such as the wire adhering to the base material or the electrode coming into contact with the electrode and interrupting the welding. Further, when the arc length L or the distance between the wire and the base metal is too long (4), the arc and the welding bead are disturbed due to the migration of the unstable wire droplets that have grown large and welding defects are likely to occur. On the other hand, (2)
It was found that in the states of (3) and (3), the transfer of wire droplets 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 (2) and (3), a judgment reference value m of the number of short circuit transitions is provided so that the number of short circuit transitions N during welding is always N ≧ m. It turns out that it is enough to control. The judgment reference value of the number of short circuit transitions may be about m = 3 to 5 (times / 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

However, if only the number of short-circuit transitions is judged, N
When <m, it is difficult to distinguish whether the wire position height is too small or too large, but it is possible to make the judgment by utilizing the characteristics of the short-circuiting transition time ratio of the wire droplet. Become. FIG. 5 shows the relationship between the arc length and the short-circuit transfer time ratio of wire droplets. In the figure, the results of changing the pulse arc current value into three types: large, medium, and small are shown. The short circuit transfer time ratio At of the wire droplet is 1 in the short circuit area.
The characteristics are such that the arc length L and the distance between the wire and the base metal decrease rapidly from 00% and then decrease to 0%. With respect to the upper limit reference value b of the short-circuit transition time ratio, when the short-circuit transition time ratio At is greater than At, the wire position height is too small and becomes an unstable region. Thus, when At <a, the wire position height is excessive and the region becomes unstable. It can be seen that the stable region of the wire droplet and the 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 transition time rate is about a = 5.
20 (%), and the upper limit reference value is about b = 80 to 95
It turns out that it is good to set each to (%). FIG.
The wire short-circuit detecting means 14 shown in FIG. 2 is used to obtain the number N of short-circuiting transitions of the wire droplet and the short-circuiting transition time ratio At, and this information is taken into the welding wire position determining means 15 to determine the quality of the wire position. . For example, when the short circuit transition time ratio At is At <a, or when the number of short circuit transitions N is N <m and At <a, it is determined that the wire position height is excessive and a downward control signal is sent to the welding controller. Call 16 Further, the short circuit transition time rate At is a ≦
When At ≦ b or when the number of short circuit transitions N is N ≧ m, it is determined that the wire position height is appropriate and the wire position height is maintained as it is. On the other hand, when At> b, or N <m, and At>
In the case of b, it is determined that the wire position height is too small, and the welding control signal is transmitted to the welding controller 16.

When the welding controller 16 receives a downward control signal from the wire position determination means 15, the torch drive shaft 4 on which the welding torch 1 and the welding wire 8 are mounted.
Is controlled in the descending direction, and 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 proper and the vertical movement control signal is not output, the height of the welding torch and the welding wire are controlled to be maintained as they are.
In addition, the operation of controlling the arc length to be constant is performed by the torch drive shaft 4
When the torch drive shaft 4 is controlled in the ascending direction or the descending direction by judging the wire position from the wire position judging means 15, the control operation with the constant arc length is stopped during the control period. Then, the control command of the wire position determination means may be followed. Further, when the wire position determining means 15 determines that the wire position height is proper, the control operation with a constant arc length may be restarted so as to maintain the wire position height, and the torch drive shaft may be continuously controlled. .

By thus controlling the torch drive shaft on which the welding torch and the welding wire are mounted, the height of the wire position can be properly controlled, and the wire droplets are not disturbed and the welding bead is not defective. It is possible to always obtain stable wire droplet transfer and good welding results.

FIG. 6 shows an embodiment of the present invention for diagnosing abnormalities in the welding wire and the electrode. Reference numeral 23 denotes a non-energized welding wire 8 sent into the arc 2 and an electrode where the arc 2 is generated. Electrode voltage signal 22 of voltage Ve generated between 2 and
Is an electrode voltage detecting means for detecting the
Voltage Ea generated between the electrode 2 and the base material 5 where
Is a welding voltage detecting means for detecting the welding voltage signal 25 of FIG. Further, 24 is an abnormality determining means for determining an abnormality of the welding wire and the electrode, and uses the electrode voltage signal Ve and the welding voltage signal Ea transmitted from the electrode voltage detecting means 23 and the welding voltage detecting means 26 as the reference voltage e2 for abnormality determination. The presence or absence of abnormality is determined by comparison. When the abnormality determining means 24 determines that there is an abnormality, a welding stop instruction and an electrode abnormality display instruction are transmitted to the welding controller 16.

FIGS. 7 and 8 show examples of the signal waveforms of the welding voltage Ea and the electrode voltage Ve during welding. In the figures, ts is the short-circuit transition time of the wire droplet, and ta is It represents the contact time of the electrodes. As can be seen from comparison with the signal waveform of the wire voltage Vw shown in FIG. 3, when the wire droplet makes a short-circuit transition (short-circuit transition time ts), the level of the wire voltage Vw drops to near 0 V, whereas the electrode voltage Ve has the characteristic of rising to the level of the welding voltage only during the short circuit transition time ts. In FIG. 7, at the point ta where the level of the electrode voltage Ve has dropped to near 0 V, when the disturbed droplet of the welding wire contacts the electrode, the arc 2 is generated as it is, and therefore the welding voltage is small. It shows how it changes to. On the other hand, when the electrode 2 and the welding wire 8 come into contact with the molten pool of the base material 5 (contact time ta), the levels of the welding voltage signal Ea and the electrode voltage signal Ve decrease to near 0V as shown in FIG. When such a contact phenomenon occurs, not only is the electrode damaged and consumed abnormally, but if welding is continued as it is, it is difficult to continue a normal arc, and a welding defect occurs.

In order to prevent this, a reference voltage e2 for contact determination is provided here, and the levels of the welding voltage Ea and the electrode voltage Ve are monitored by the abnormality determination circuit. Then, during the welding period, when the welding voltage signal Ea is Ea ≦ e2, it is determined that the electrode is in contact with the molten pool, and when the electrode voltage signal Ve is Ve ≦ e2, the droplet of the welding wire is in contact with the electrode. The welding stop command and the electrode abnormality display command are transmitted to the welding controller 16. It is desirable that the reference voltage e2 for contact determination is set to be larger than 0 and about 3 V or less in consideration of contact resistance and cable resistance. With such a configuration, it is possible to minimize consumption due to contact with the electrode, and prevent occurrence of welding defects and deterioration of welding quality due to troubles of the welding wire and the electrode.

By equipping the automatic welding system with the control function of the welding wire position of the present invention, it is possible to realize various welding joints.
Appropriate control of the welding wire position and electrode abnormality determination can be performed for pass welding and multi-layer multi-pass welding, and automation of welding and improvement of welding quality can be achieved. For example, it can be applied to automatic welding of a chemical plant and a nuclear power plant having many welded pipes.

[0026]

By using the welding wire position detecting method and apparatus of the present invention, it is possible to easily determine the quality of the welding wire, which is related to the quality of the welding bead shape.
The wire height can be properly controlled, and good welding results of the welding 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. It is possible to prevent the deterioration of the result. Further, 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, welded pipes, and welded assemblies of chemical plants and nuclear power plants. Alternatively, even for multi-layer multi-pass welding, proper detection of the welding wire position and abnormality diagnosis of the electrode can be performed, so that not only beginners can easily perform welding, but also it is easy to use, automation of welding and welding quality Can be improved.

[Brief description of drawings]

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

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

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

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

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

FIG. 6 is a block diagram of an embodiment showing the contents relating to the diagnosis of the welding wire and the electrode of the present invention.

FIG. 7 is a waveform diagram of typical welding voltage and wire-electrode voltage determined by the abnormality diagnosis of the welding wire and electrode of the present invention.

FIG. 8 is another waveform diagram of a typical welding voltage and wire-electrode voltage determined by the welding wire and electrode abnormality diagnosis of the present invention.

[Explanation of symbols]

1 ... Welding torch, 2 ... Electrode, 3 ... Torch holder, 4 ... Torch drive shaft, 5 ... Base metal, 6 ... Arc, 7 ... Welding power supply, 8
... welding wire, 9 ... wire guide, 10 ... wire holder, 11 ... traveling carriage, 12 ... traveling rail, 13 ... wire voltage detecting means, 14 ... wire short circuit detecting means, 15 ... welding wire position determining means, 16 ... welding controller.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiko Mizuguchi 3-1-1, Saiwaicho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi factory (72) Inventor Yuji Yamaguchi 3-chome, Saiwaicho, Hitachi, Ibaraki No. 1 Hitachi Ltd. Hitachi factory

Claims (8)

[Claims] 1. A non-consumable welding wire is fed between the base metal of the welded joint and the non-consumable electrode at the tip of the welding torch to generate an arc of arbitrary output waveform, and to feed the non-energized welding wire into the arc and into the molten pool. While detecting a welding wire position when performing welding, wire voltage detecting means for detecting a wire voltage signal generated between the non-energized welding wire and the welding base material, and detecting a short-circuit transition of the welding wire A wire short circuit detection means is provided, and a wire position discrimination means for discriminating the position of the welding wire is provided, and during the welding period after the arc is generated, the wire voltage signal is taken into the wire short circuit detection means and the reference voltage of the wire short circuit is obtained. Then, the number of short-circuit transitions per unit time of the welding wire and the short-circuit transition time rate are obtained, and the number of short-circuit transitions and the short-circuit transition time rate are determined based on the wire position. Means for determining whether the position of the welding wire is good or bad, and when the wire position determining means determines that the height of the position of the welding wire is excessive, the control signal for lowering the height is oppositely applied to the welding. A method for detecting the position of a welding wire, characterized in that when it is determined that the height of the wire is too small, a control signal for raising the height is emitted. 2. The short-circuit transfer time ratio At is At <a (%), or the short-circuit transfer time ratio At is At <a (%) and the short-circuit transfer count N is N <m (claim 2). (Number of times / second), it is determined that the welding wire position height is excessive and inappropriate, and conversely, when the short circuit transition time ratio At is greater than At> b, or when the short circuit transition time ratio At is At>
b and the number of short circuit transitions (N) is N <m, it is determined that the welding wire position height is too small, and a ≦ A
A welding wire position detecting method for determining that the welding wire position height is appropriate when t ≦ b and N ≧ m. 3. The method according to claim 1 or 2, wherein the judgment reference value m of the number of short circuit transitions is m = 3 to 5 (number / second).
And the lower limit reference value a of the short circuit transition time rate is a = 5 to 20
(%), And the upper limit reference value b of the short circuit transition time ratio is b =
80-99 (%) and the method of detecting the welding wire position determined respectively. 4. An electric arc is generated between the base metal of the welded joint and the non-consumable electrode at the tip of the welding torch to generate an arc of arbitrary output waveform, and a non-energized welding wire is fed into the arc and into the molten pool. While detecting the welding wire position when performing welding, wire voltage detection means for detecting a wire voltage signal generated between the non-energized welding wire and the welding base metal, and during the welding period after arcing, After detecting the short-circuit transition of the welding wire by capturing the wire voltage signal and comparing it with the reference voltage of the wire short-circuit, a wire short-circuit detecting means for determining the number of short-circuit transitions per unit time of the welding wire and the short-circuit transition time ratio is provided,
A control for taking in the number of short-circuit transitions and the short-circuit transition time ratio obtained by the wire short-circuit detection means to determine the quality of the welding wire position, and lowering the height of the welding wire position when it is determined to be excessive A welding wire position detecting device, further comprising wire position discriminating means for transmitting a control signal for raising the height of the signal when the height of the welding wire is judged to be too small. 5. A non-consumable welding wire is fed into the arc and into the molten pool by energizing between the base metal of the welded joint and the non-consumable electrode at the tip of the welding torch to generate an arc of arbitrary output waveform. In the method for detecting the position of a welding wire when performing welding, an electrode voltage detecting means for detecting an electrode voltage signal Ve generated between the non-conducting welding wire and a non-consumable electrode, and the electrode through which a welding current flows Welding voltage detection means for detecting a welding voltage signal Ea generated between the welding base metal and the welding base metal, and further provided with abnormality determination means for determining an abnormality of the electrode and the welding wire, during the welding period after arcing, The electrode voltage signal Ve and the welding voltage signal Ea are taken into this abnormality determining means, and when the electrode voltage signal Ve is Ve ≦ e2 with respect to the reference voltage value e2 for abnormality determination, the droplets of the welding wire come into contact with the electrodes. If the welding voltage signal Ea is Ea ≦ e2 with respect to the reference voltage value e2 for abnormality determination, it is determined that the electrode has come into contact with the molten pool, and a welding stop command and an electrode abnormality display command are issued. A method for detecting the position of a welding wire, characterized in that. 6. An electric current is generated between a base material of a welded 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-energized welding wire is formed in the arc and in a molten pool. In a welding wire position detecting device for performing welding while feeding, electrode voltage detecting means for detecting an electrode voltage signal Ve generated between the non-conducting welding wire and the non-consumable electrode, and a welding current flowing therethrough. A welding voltage detecting means for detecting a welding voltage signal Ea generated between the electrode and the welding base material is provided, and further, during the welding period after the arc is generated, the electrode voltage signal Ve and the welding voltage signal Ea are taken in to determine an abnormality. When the electrode voltage signal Ve is Ve ≦ e2 with respect to the reference voltage value e2 of, it is determined that the droplet of the welding wire has contacted the electrode, and
When the welding voltage signal Ea is Ea ≦ e2 with respect to the reference voltage value e2 for abnormality determination, an abnormality determination means for determining that the electrode has contacted the molten pool is provided, and a command to stop welding and an electrode abnormality display command are issued. A welding wire position detecting device characterized in that 7. An automatic welding system comprising the welding wire position detection device according to claim 4 or 6. 8. An automatic welding system using the method for detecting the position of a welding wire according to claim 1, 2, 3, or 5.