JP3229014B2 - AC non-consumable electrode arc welding apparatus and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arc welding apparatus, and more particularly to an AC TIG arc welding apparatus suitable for automatically welding aluminum using an additive wire.

[0002]

2. Description of the Related Art FIG. 6 shows a configuration of a welding apparatus generally used conventionally as an AC TIG welding method for aluminum and aluminum alloys. An AC arc power supply 34 is connected to the tungsten electrode 32 and the aluminum-based base material 33 in the TIG welding torch 31, and an AC arc 35 is formed between the tungsten electrode 32 and the base material 33 in an argon shielding gas. A welding wire 36 for welding is fed from a wire feeder 37 through a conduit 38 and a contact tip 39 connected to the conduit 38, and then to the TIG torch 31.
From the outside of the gas shield nozzle 41 at the tip of the base material 3
3 and is inserted toward the molten pool 42 and is in contact with the base material 33.

By the way, when performing TIG welding using a cold wire, as shown in FIG. 7, an additional wire 36 is separated from a tungsten electrode 32 forming an arc 35 by a distance of approximately 3 mm or less between surfaces and is substantially parallel to the tungsten electrode 32. When the TIG torch 31 having the shield nozzle 41 is configured to be fed toward the molten pool, the entire size of the torch 31 including the wire guides such as the contact tip 39 is very compact. However, in this case, in the conventional method, the tip of the wire 36 is
Since the wire 36 is equal to the base material potential, the arc 35 crawls from the base material 33 along the wire 36 when the distance between the tungsten electrode 32 and the base material 33 happens to be slightly longer such as 5 mm. As a result, the arc 35 and the melting stability of the wire 36 are significantly impaired, and the molten wire 36 often comes into contact with the tungsten electrode 32 to form the electrode 3.
2 contaminates and makes it impossible to continue the welding operation.

In the AC arc, when the tungsten electrode 32 is positive, the cathode spot of the arc 35 runs around the surface of the base material 33 and the wire 36 in search of an oxide which easily emits thermionic electrons.
Crawling up on the wire 36 occurs remarkably,
It is much more difficult to maintain the arc 35 than in the case of a DC arc where the tungsten electrode 32 is limited to minus. The reason is that in the DC TIG arc, the arc 35 is formed with the polarity that the tungsten electrode 32 becomes negative. However, since the tungsten electrode 32 is a hot cathode having excellent thermoelectron emission ability, the cathode point of the arc 35 is
Formed stably on top.

[0005] When the wire feeding speed is slow, FIG.
As described above, the tip of the wire 36 is separated from the base material 33 and melts in the arc plasma, and a large droplet 44 comes into contact with the tungsten electrode 32 to contaminate the tungsten electrode 32.
In some cases, it may be damaged, making welding impossible.

Therefore, conventionally, in order to avoid such a state, the wire 36 is separated from the tungsten electrode 32 as much as possible, and the tip of the wire 36 is connected to the molten pool 4 on the base material 33.
2 had been inserted. For example, as shown in FIG. 6, the wire insertion angle θ must be 60 degrees or less, and therefore, the wire 36 is usually inserted from outside the gas shield nozzle 41 of the torch 31, and eventually the configuration around the torch is completed. Was getting bigger. Therefore, there was a problem that welding in a narrow part was difficult. The torch 31 is a base material 33
There is a problem that when the wire 36 is slightly moved up and down, the insertion position of the wire 36 greatly changes. Due to these problems, it has not been practically used to mount and weld a TIG welding torch with an addition wire to an articulated welding robot.

[0007] Regarding DC TIG welding,
As shown in FIG. 7, a technique for enabling welding while inserting the wire 36 close to and in parallel with the tungsten electrode 32 is disclosed in a patent application (Japanese Unexamined Patent Publication No. 63-180736) filed by the present applicant. No.). In this patent application invention, when the wire 36 is in contact with the base material 33, the arc current is stopped, and the arc current is applied only while the wire 36 is separated from the base material 33. Arc 35 toward 36 side
Is prevented from occurring.

[0008]

As described above, the welding apparatus shown in FIG. 6 has a large structure, and when the torch 31 is slightly moved up and down with respect to the base material 33, the insertion position of the wire 36 is greatly changed. Therefore, it has not been practically used in articulated welding robots and the like. In addition, the patent application of the present inventors is compact, and the welding progress direction can be selected in any direction, and is suitable for mounting on a welding robot. However, since it is for a DC TIG welding device, its use range is limited. It had been. That is, during the AC TIG welding of aluminum, the arc must be extinguished and re-ignited every time the polarity of the arc current changes. For this reason, the arc tends to be unstable, and it is difficult to maintain the arc by the method of the patent application. Therefore, there is a problem that it is difficult to apply to welding of aluminum using AC TIG.

SUMMARY OF THE INVENTION It is an object of the present invention to form a stable arc using an alternating current, to reduce the size of the torch, to make it easier to weld a narrow part, and to provide an additional wire suitable for mounting on an articulated welding robot. It is an object of the present invention to provide a device capable of performing TIG welding with a mark.

[0010]

The above object of the present invention is achieved by the following constitution. That is, the welding base metal and the non-consumable electrode and a current control means of an AC arc power supply connected to them and forming an AC arc, and an additional wire fed to the arc generating portion and an AC power supply for wire conduction were provided. In an AC non-consumable electrode arc welding apparatus, the wire is synchronized with the AC arc power source, and when the non-consumable electrode is a half-wave with a negative pole (EN), the wire is positive with respect to the base material and the non-consumable electrode is with a half of the positive pole. This is an AC non-consumable electrode arc welding apparatus provided with a wire energizing current control means for energizing the wire with an AC constant current which becomes a negative pole with respect to the base material when the wave is in the wave (EP) . Further, the AC non-consumable electrode electrode of the present invention.
In the above configuration, the tip of the additive wire is welded to the above configuration.
Wire contact detection hand that detects whether it is in contact with the base material
In addition to the steps, the wire current control means may be
Based on the wire contact signal from the ear contact detection means,
Wire conduction when the wire is in contact with the base metal
Wire when the wire is separated from the base material.
And the wire is in contact with the welding base material
When the wire is energized, it is synchronized with the AC
When the wear electrode is a half-wave with a negative pole, the wire
When the positive electrode and non-consumable electrode are half-wave of positive electrode, the wire
Pass a constant negative current through the wire
It is good also as a structure which supplies electricity.

Here, the current control means of the arc power supply detects a high arc current of 180 A or more when the wire contact detection means detects the contact of the base material of the wire, and a low arc current of 180 A or less when the wire is separated from the base material. The arc current is controlled so that
An AC constant current of 0 A to 80 A can be supplied to the wire. Also, the current control means of the arc power supply may control the arc current during the detection of the base metal contact of the wire by the wire contact detection means so that the average arc current becomes a set value.

The wire contact detecting means detects a voltage between the wire energizing tip and the base material. When the non-consumable electrode is negative, a negative voltage is applied. When the non-consumable electrode is positive, a high voltage is applied by a positive voltage. Signal voltage that is pulled up through the circuit, and the absolute value of the detected voltage is 3 V
In the following cases, it can be determined that the wire is in contact with the base material.

Further, H for converting a DC power supply to an AC power supply.
An H-bridge for converting a DC power supply to an AC power supply, comprising a wire conduction current control means comprising two sets of arms comprising a bridge and two transistors which switch in a saturated state connected in series; The H-bridge is provided with a wire conduction current control means composed of four sets of circuit elements in which a forward diode and a transistor switching in a saturated state are connected in series, or An H-bridge for converting a power supply into an AC power supply. The H-bridge is composed of two sets of a forward diode, a transistor that switches in a saturated state, and a transistor that controls a constant current in an unsaturated state, which are connected in series. It is possible to adopt a configuration provided with a wire conduction current control means composed of an arm.

The additive wire is substantially parallel to the non-consumable electrode and the distance between the non-consumable electrode and the surface of the wire is 3 m.
m may be arranged close to each other.

The above object of the present invention is also achieved by the following constitution. That is, in the AC non-consumable electrode arc welding method of feeding an additional wire to the AC arc forming portion between the welding base material and the non-consumable electrode and welding the base material, the current flowing through the wire and the current flowing through the AC arc power supply are opposite to each other. AC non-consumable electrode arc welding method for applying a synchronized current, or the wire conduction current and the AC arc power supply current conduct synchronous currents in opposite directions, and stop the wire conduction when the wire is separated from the base material. This is an AC non-consumable electrode arc welding method in which the arc current is made lower than a set value at the same time, and the wire is energized when the wire is in contact with the base material, and at the same time, the arc current is equal to or more than the set value.

[0016]

As generally known as a magnetic blowing phenomenon of an arc, when the direction of current flow between the wire current and the arc current is the same, the arc is drawn to the wire side by the electromagnetic force between the two, and the wire current and the arc current When the direction of the current is reversed, the electromagnetic force acts to move the arc away from the wire. Therefore, when the arc is EN half-wave, the arc is moved away to the extent that the anode point of the arc does not crawl on the wire, and when the arc is EP half-wave, the cathode point of the arc determines oxide. Therefore, even if slight climbing is recognized, the staying time is shortened, and the melting of the wire progresses, and droplets are not formed.

As described above, when the wire is in contact with the base material, an electric current in a direction opposite to the arc current is applied to the wire, so that the arc is blown magnetically in a direction away from the wire. Arcing is less likely to occur. Also, when the wire is separated from the base material, the current supply to the wire is stopped, and the arc current is reduced. As a result, it is possible to prevent the droplet at the tip of the wire from contacting the non-consumable electrode. In order to exhibit such an effect, it is sufficient that the wire current is 20 A to 80 A for an AC arc having an average arc current of 180 A to 350 A.

When the present invention is applied to welding of aluminum, aluminum alloy, or the like, it is not necessary to increase the wire current. That is, the main purpose of the wire energization in the present invention is not the concept of a hot wire that melts the wire at high speed by resistance heating, but the energization to keep the arc away from the wire by the electromagnetic force of the wire current. If the wire current is further increased, a phenomenon occurs in which the wire is melted or softened and the wire is blown off by the electromagnetic force. Therefore, in the case of the average arc current value, the upper limit of the wire current is 80.
It was about A. When the wire current is set to 20 A or less, the effect of keeping the arc away from the wire is reduced, so that a droplet is easily formed and the welding operation cannot be continued.

When the wire feeding speed is low, the wire melts due to radiant heat from the arc plasma, and the tip of the wire separates from the base material and floats in the arc plasma, where droplets grow more and more. I do. However, when the arc current is a predetermined value (for example, 180 A or less), the growth of this melting is considerably slow. When the wire speed is higher than the predetermined speed, the wire is again formed before the droplet at the tip of the wire grows too much. It comes into contact with the material. On the other hand, if the wire speed is reduced while the arc current is kept high, the wire separates from the base material and a droplet grows, and immediately contacts the non-consumable electrode to make welding impossible. Therefore, in the present invention,
Even when a high-current arc is generated, if the tip of the wire separates from the base material, the arc current is immediately reduced to a predetermined value (for example, 180 A or less), so that the droplet contacts the base material before it grows large. Therefore, it is possible to prevent a situation in which the droplet contacts the non-consumable electrode.

[0020]

FIG. 1 shows an embodiment of the present invention.
The wire 6 is sent from a wire feeder (not shown) to the TIG torch 12, and a 1.6 mm diameter aluminum addition wire 6 from the inside of the shield nozzle 10 of the TIG torch 12 is substantially parallel to the 3.2 mm diameter tungsten electrode 2. And into the molten pool 11 from a position where the distance between the surfaces is close to 1 to 3 mm. One output terminal of the wire power supply 14 is connected to the additional wire 6 via the contact tip 9 in the torch 12, and the other output terminal is connected to the base material 3.

One output terminal of the arc power supply 15 having the AC constant current characteristic is connected to the tungsten electrode 2 in the torch 12, the other terminal is connected to the base material 3, and an AC arc is provided between the tungsten electrode 2 and the base material 3. 5 is formed. In the torch 12, the tungsten electrode 2 and the wire 6 are sufficiently insulated from each other so that no arc is generated between them.

The wire power supply 14 has a diode D on the secondary side of an output transformer T of an inverter type power supply controlled by a constant current.
5, after the DC power supply unit configured with D6
An H-bridge 16 constituted by a set of switching transistors TR1 to TR4 is incorporated to output a square wave alternating current. Note that diodes D1 to D4
Is for reverse current bypass for protecting the transistors TR1 to TR4. An arc current detection circuit 18 using a current sensor 17 composed of a Hall element detects a current waveform of an AC arc, and a polarity discrimination circuit 19 detects whether the tungsten electrode 2 has a positive half-wave polarity (EP) or a negative half-wave. (EN), and based on the output signal, controls the drive circuit 20 for the transistors TR1 to TR4 constituting the H bridge 16 so that a current always in the opposite direction to the arc current flows through the wire 6. To

In order to determine whether the tip of the wire 6 is in contact with the base material 3, a voltage Vw between the contact tip 9 and the base material 3 is detected, and its absolute value is higher or lower than 3V. Is determined by the touch detection circuit 21. That is, when the voltage is lower than 3 V, it is determined that the tip of the wire 6 is in contact with the base material 3, and the transistors of the set of transistors TR1 and TR4 and the set of transistors TR3 and TR2 constituting the H bridge 16 are turned on alternately. Outputs AC current, but 3V
When it is higher, the tip of the wire 6 is interpreted as being separated from the base material 3 and the transistor TR forming the H bridge 16 is interpreted.
1 to TR4 are all turned off, and the supply of the wire current is stopped.

In detecting the voltage Vw between the contact chip 9 and the base material 3, a pull-up voltage circuit 22 is provided, and an AC pull of ± 15 V which always has the same polarity as the arc voltage is provided on the contact chip 9 side. Up voltage with resistance R
1 is applied.

The output signal of the touch detection circuit 21 is also transmitted to the arc current control circuit 23, and the wire 6
Is touched, a large arc current of 180 A or more, such as 300 A, is controlled. When the wire 6 is separated from the base material 3, the arc current is controlled to a constant low current of 180 A or less, such as 160 A.

On the other hand, since the melting of the base material 3 is greatly affected by the arc current, the arc current is detected, and the wire 6 touches the base material 3 by the average current control circuit 24 so that the average arc current becomes constant. To form a signal that controls the arc current when it is running. The wire current is, for example, an average arc current of 23.
A constant current of 30 A is supplied when the current is about 0 A, and a constant current of 60 A is supplied when the average arc current is about 300 A.

FIG. 2 is a view for explaining the relationship among the arc current, the wire current, and the wire contact state during welding using the apparatus of FIG. On a base material of aluminum alloy A5083, a 60 Hz square-wave AC arc power supply was used, the average arc current was set to 300 A, and a wire current of 60 A and A5356 aluminum wire having a diameter of 1.6 mm were converted to 4 m / m.
The state in which the beads are fed by feeding in and placed is simulated.

Since the welding apparatus of this embodiment has the above-described configuration, it operates as follows. In the case of aluminum welding, when the arc electrode is positive (EP), the cathode spot of the arc 5 is basically generated from the oxide on the surface of the base material 3.
This is because aluminum easily emits thermoelectrons and easily forms a cathode spot of the arc 5. However, when the arc 5 is generated, the oxide is immediately decomposed by heat and disappears, and the arc 5 moves for another oxide, and thus the welding proceeds. When the wire 6 is in contact with the base material 3,
The wire 6 has substantially the same potential as the base material 3, and if there is an oxide on the surface of the wire 6, an arc 5 is generated therefrom. However, if a wire current flows in the opposite direction to the arc current,
Due to the repulsion of the electromagnetic force, the tendency that the arc 5 goes up to the position above the wire 6 in search of the cathode point is suppressed.

Therefore, when the arc 5 is an EN half-wave,
The arc 5 is so far away that the anode point of the arc 5 does not creep up on the wire 6, and when the arc 5 is an EP half-wave, the cathode point of the arc 5 crawls on the wire 6 in search of oxide. Since the attempt is made to control, the melting of the wire does not proceed to form droplets 13 (see FIG. 3). In order to exhibit such an effect, an average arc current of 180 A
For an AC arc of ~ 350A, the wire current is 20A
It was good if it was ~ 80A.

Next, when the wire feeding speed is low,
The wire melts by receiving radiant heat or the like from the arc plasma, and the tip of the wire 6 separates from the base material 3 and floats in the arc plasma, where the droplet 13 (see FIG. 3) grows more and more. However, the growth of the melt 13 is slowed by setting the arc current to 180 A or less. For example,
At a wire speed of 1 m / min or more, before the droplet 13 at the tip of the wire 6 grows too much, the wire 6 is re-formed to the base metal 3.
Comes into contact with On the other hand, if the wire speed is reduced while the arc current is kept high, such as 300 A, the wire 6 separates from the base material 3 and the droplets 13 grow and immediately contact the tungsten electrode 2 to make welding impossible. In this embodiment, when the tip of the wire 6 separates from the base material 3 even during the generation of an arc of 350 A, the arc current is immediately reduced to 160 A or the like. As a result, the contact between the droplet 13 and the tungsten electrode 2 is prevented.

By the way, if the wire conduction is continued due to some mistake when the tip of the wire 6 separates from the base material 3, for example, as shown in FIG. In the case of the EP half-wave, the path indicated by the broken line, that is, the arc power supply 15 → the tungsten electrode 2 → the arc 5 → the wire 6 → TR4 → D2 → the base material 3 → the arc power supply 15
Although the path is not shown in the case of EN half-wave, it flows along the path of arc power supply 15 → base metal 3 → D1 → TR3 → wire 6 → arc 5 → tungsten electrode 2 → arc electrode 15. An arc 5 is formed between the tungsten electrode 2 and the tip of the wire 6, and a large droplet 13 is formed immediately at the tip of the wire 6.

However, as soon as the tip of the wire 6 is separated from the base material 3, the transistor TR1 forming the H bridge
When all of .about.4 are turned off, the wire 6 becomes an electrically floating form, so that the arc current does not flow to the wire power supply 14, and the arc 5 is not formed between the wire 6 and the tungsten electrode 2.

FIGS. 4 and 5 show the principle of the power circuit of the wire power supply 14 according to another embodiment of the present invention.
When the separation / contact between the wire and the base material 3 cannot be correctly detected, the function of suppressing the arc current from flowing into the wire power supply as low as possible is provided.

The circuit of the wire power supply 25 shown in FIG. 4 provides a path through which the arc current described with reference to FIG.
A forward diode D is connected in series with each of the transistors TR1 to TR4.
It shuts off by putting in 7-10. by this,
The arc current flowing into the wire power supply 25 has been greatly reduced. However, when the wire is energized, that is, TR1
When any one of .about.4 is conducting, it sometimes flows through the power transformer T and the rectifier diodes D5 and D6 as shown by a broken line in FIG. 4, for example.

In the circuit of the wire power supply 26 shown in FIG. 5, the H bridge is constituted by four sets of FET transistors, and FET1 and F
ET3 switches in saturation, FET2 and FET4
Is to control the gate voltage to control the constant current in the unsaturated region. Diodes D7 and D8 are connected in series to each arm of the H-bridge.

The effect of this embodiment is that the touch detection circuit 21 (see FIG. 1) does not function well and the wire 6
Even if the wire 6 is energized by being erroneously determined to be in contact even when separated from the
4 is that the constant current control is performed, so that only the set wire current flows into the wire 6 for the arc current. For example, even if the arc current is 350 A, when the wire current is set to a constant value (60 A),
Even if the wire 6 is separated from the base material 3 and an arc 5 is generated between the tungsten electrode 2 and the wire 6, only an arc current of 60 A enters the wire 6, and the growth of the droplet 13 is caused by an arc of 350 A. It is much slower than the case where all of the droplets 13 enter the wire 6, and the contact of the droplet 13 with the tungsten electrode 2 is less likely to occur.

Since the FET 1 and the FET 3 are switched in a saturated state, there is no function of controlling the current to a constant current.
Therefore, if the tungsten electrode 2 is positive and the wire 6
When the wire 6 is separated from the base material 3 when the negative polarity is in the state, the total arc current is increased from the tungsten electrode 2 to the arc 5 to the wire 6 when there are no diodes D7 and D8.
→ DF3 → FET1 → base material 3 can flow. Therefore, in this embodiment, a diode D7 is provided for each arc of the H bridge.
D8 is inserted to block this path. At the same time, the path of the tungsten electrode 2 → arc 5 → wire 6 → FET4 → DF2 → base material 3 as shown by the broken line in FIG.
Since this path contains the FET 4, the current is controlled to a constant wire current there.

As described above, it is important to determine whether the wire 6 is separated from or in contact with the base material 3. For example, a 1.6 mm diameter aluminum-based wire 6 is used. The voltage between the contact chip 9 and the base material 3 when the extension is 75 mm and the wire current is applied at 80 A is maintained at 0.3 V or less. On the other hand, when the wire 6 separates from the base material 3 and the wire tip floats in the arc 5, the plasma potential near the tip of the wire 6 ±
Since a voltage of 4 to 12 V is detected, in the case of a low-resistance wire such as aluminum or an aluminum alloy, by monitoring the wire voltage while the wire is energized, for example, 3
If it is V or more, the wire 6 is separated from the base material 3, and if it is 3 V or less, it can be determined that the wire 6 is in contact with the base material 3. In addition,
In the case of a mild steel hot wire TIG using a mild steel wire having a diameter of 1.2 mm, since the resistance of the wire 6 is high,
The voltage drop in the wire heating section during contact energization may be as large as 5 V, and it is not possible to accurately detect wire separation from the wire voltage during wire energization. Also, when the wire 6 is far away from the arc 5 and goes out of the plasma, the voltage from the arc 5 is not applied, so that the voltage becomes 0 V, so that it is impossible to distinguish from the contact. So Figure 1
As shown in (2), when the pull-up voltage formed by the pull-up voltage forming circuit 22 is applied through a high resistance R1 such as 1 kΩ, the pull-up voltage is detected when the wire 6 goes out of the plasma of the arc 5. And become identifiable from contact.

If the pull-up voltage has a polarity opposite to that of the tungsten electrode 2, the detection voltage may be close to 0 V depending on the position of the tip of the wire 6 due to the balance with the contacting plasma potential. In some cases, it was determined that the contact was inadvertent. However, in this embodiment, since the pull-up voltage is always the same polarity as that of the tungsten electrode 2, the detection voltage acts in a direction that does not approach the 0V side, so that there is no erroneous determination.

[0040]

According to the present invention, even in an AC TIG arc, the additive wire can be fed almost parallel to and close to the non-consumable electrode, so that a small torch structure can be used for metal such as aluminum or aluminum alloy. TIG welding can now be performed. Then, it is mounted on a multi-joint welding robot, so that TIG welding of a metal such as aluminum or aluminum alloy with an addition wire can be easily performed, automation is promoted, and the quality of the product is stabilized.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a circuit principle of an AC TIG welding apparatus according to one embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of the device of FIG.

FIG. 3 is a diagram illustrating the operation of the circuit of the device of FIG. 1;

FIG. 4 is an explanatory diagram of the circuit principle of the AC TIG welding apparatus according to one embodiment of the present invention.

FIG. 5 is an explanatory diagram of the circuit principle of the AC TIG welding apparatus according to one embodiment of the present invention.

FIG. 6 is an explanatory view of a conventionally used TIG welding apparatus.

FIG. 7 is an explanatory diagram of a problem in TIG welding.

FIG. 8 is an explanatory diagram of a problem in TIG welding.

[Description of Signs] 2 ... Tungsten electrode, 3 ... Base material, 5 ... Arc, 6 ... Wire, 9 ... Contact tip, 10 ... Shield nozzle,
11 ... molten pool, 12 ... TIG torch, 13 ... droplet, 14
... wire power supply, 15 ... arc power supply, 16 ... H bridge,
17 current sensor, 18 current detection circuit, 19 polarity discrimination circuit, 20 transistor drive circuit, 21 touch detection circuit, 22 pull-up voltage forming circuit, 23 arc current control circuit, 24 average current control circuit , 25, 26 ...
Wire power supply, T transformer, TR1-4 transistor, FET1-4 FET transistor, D1-6, D
F1-4: Diode

──────────────────────────────────────────────────続 き Continued on the front page (72) Masahiro Tsunoda 1-2-1-10 Isogo, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Inside the Bubcock Hitachi Co., Ltd. Kure Factory Yokohama Engineering Center (72) Inventor Tamotsu Kimine Kure-shi, Hiroshima 5-3 Takaracho Bab Hitachi Industrial Co., Ltd. (56) References JP-A-56-131071 (JP, A) JP-A-4-123873 (JP, A) JP-A-3-52768 (JP, A) JP-A-3-238172 (JP, A) JP-A-61-144273 (JP, A) JP-A-2-280966 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 9 / 167 B23K 9/073 B23K 9/127

Claims (11)

(57) [Claims] A current control means for an AC arc power supply connected to the welding base metal and the non-consumable electrode and for forming an AC arc; an additional wire fed to the arc generating portion and an AC power supply for energizing the wire; In an AC non-consumable electrode arc welding device equipped with a, the wire is synchronized with the AC arc power supply, and when the non-consumable electrode is a negative half-wave, the wire is positive with respect to the base material, and when the non-consumable electrode is a positive half-wave, An AC non-consumable electrode arc welding apparatus, comprising: a wire energizing current control means for applying an AC constant current, which is a negative pole to the base material, to the wire. 2. A wire contact detecting means for detecting whether or not the tip of an additional wire is in contact with a welding base material; and a wire contacting the welding base material based on a wire contact signal from the wire contact detecting means. When the wire is separated from the base metal , the wire current is stopped, and when the wire is separated from the base metal, the wire is in contact with the base metal.
When the wire is energized, it is synchronized with the AC arc power supply.When the non-consumable electrode has a negative half-wave, the wire is positive with respect to the base material, and when the non-consumable electrode has a positive half-wave, the wire is connected to the base metal. The AC non-consumable electrode arc welding apparatus according to claim 1, further comprising a wire conduction current control means for supplying an AC constant current, which is a negative pole to the wire, to the wire. 3. The current control means of the arc power supply has a high arc current of 180 A or more when wire contact is detected by the wire contact detection means, and a low arc current of 180 A or less when the wire is separated from the base material. 3. The AC non-consumable electrode arc welding apparatus according to claim 2, wherein the arc current is controlled as described above, and the wire energizing current control means applies an AC constant current of 20 A to 80 A to the wire. 4. The wire contact detecting means detects a voltage between the wire energizing tip and the base material, and outputs a negative voltage when the non-consumable electrode is negative and a positive voltage when the non-consumable electrode is positive via a high resistance. The AC non-consumable electrode arc according to claim 2, wherein a signal voltage that is pulled up is applied to the wire, and when the absolute value of the detected voltage is 3 V or less, it is determined that the wire is in contact with the base material. Welding equipment. 5. The current control means of the arc power supply controls an arc current during a period in which the wire contact detection means detects a base material contact of the wire such that the average arc current becomes a set value. An AC non-consumable electrode arc welding apparatus as described. 6. A transistor 2 having an H-bridge for converting a DC power supply to an AC power supply and switching in a saturated state.
Ke is claim 1 Symbol mounting, characterized in that it comprises a wire energization current control means which is composed of two pairs of arms which are connected in series AC non-consumable electrode arc welding device. 7. An H-bridge for converting a DC power supply to an AC power supply, the H-bridge comprising four sets of circuit elements formed by connecting a forward diode and a transistor switching in a saturated state in series. It has been that the wire energization current control means and alternating non-consumable electrode arc welding apparatus according to claim 1 Symbol mounting, characterized in that it comprises a. 8. An H-bridge for converting a DC power supply to an AC power supply, wherein the H-bridge has a forward diode, a transistor that switches in a saturated state, and a transistor that controls a constant current in an unsaturated state, connected in series. things claim 1 Symbol mounting, characterized in that comprises a wire energization current control means which is composed of two pairs of arms that are configured alternating non-consumable current arc welding apparatus. 9. The doping wire is substantially parallel to the non-consumable electrode,
And non-consumable electrode and the distance between the surface of the wire of claim 1 Symbol mounting, characterized in that it is arranged close to be within 3mm alternating non-consumable electrode arc welding device. 10. An AC non-consumable electrode arc welding method in which an additional wire is fed to an AC arc forming portion between a welding base material and a non-consumable electrode to weld the base material. An AC non-consumable electrode arc welding method, characterized in that synchronous currents in opposite directions are supplied. 11. An AC non-consumable electrode arc welding method in which an additional wire is fed to an AC arc forming portion between a welding base material and a non-consumable electrode to weld the base material, Synchronous currents in opposite directions are applied.When the wire is separated from the base material, the current is stopped.At the same time, the arc current is reduced below the set value.When the wire is in contact with the base material, the wire is turned off. An AC non-consumable electrode arc welding method, characterized by energizing and simultaneously setting an arc current to a set value or more.