JPH0712540B2 - Arc welding method and apparatus, and flux cored wire - Google Patents

Description

TECHNICAL FIELD The present invention relates to an arc welding method and apparatus, and a flux cored wire.

[Prior Art] Conventionally, consumable electrode type arc welding methods such as gas shielded arc welding, submerged arc welding, and self shielded arc welding have been widely used.

For example, according to the gas shielded arc welding method, the working current range is high, the welding speed is high, the welding efficiency is high (high efficiency), the occurrence of welding defects is relatively small, and the joint performance is good (high reliability). Certain shapes have advantages such as automatic welding (automation), improved performance of welding power sources such as pulse power sources, and good workability (improvement of power sources).

Also, the self-shielded arc welding method using flux cored wire is suitable for outdoor welding because it can perform excellent welding even under wind speed of about 10 m / sec.

[Problems to be Solved by the Invention] However, in the conventional consumable electrode type arc welding method, when the welding current is increased in order to obtain a large amount of welding, a bead having a tendency to overlap is formed at a low speed when spattering occurs. Also occurs frequently. In particular, when the shield gas is (CO ₂ ) 100% in the gas shield arc welding method, this tendency is strong, the bead appearance is deteriorated, and defects are likely to occur during multi-layer welding.

Further, in the conventional consumable electrode type arc welding method, when the welding current is increased for high speed welding, undercuts and irregular beads are formed.

Furthermore, in the self-shielded arc welding method, the droplet transfer form does not become a complete spray transfer but is a globular + spray type, so there is no directivity, shallow penetration, and spatter is considerable. There is a drawback that there are many.

Therefore, slag entrainment and fusion failure are likely to occur in the narrow overflow portion that occurs in the process of the initial layer or the multi-layer welding in the welding with the backing metal in the downward and sideways postures.

Also, in downward and horizontal fillet welding, it is difficult to secure the penetration of the root portion.

Further, in self-shielded arc welding, the flux contained in the flux cored wire is provided with functions such as shield gas generation, slag generation, deoxidation and denitrification. For this reason, the flux is formed by mixing various granular materials having different bulk densities. Therefore, when the flux containing such various powders and particles is included in the wire, it is expected that the components will be biased, resulting in the occurrence of welding defects.

That is, the self-shielded arc welding method is a welding method that is rarely used although it has the advantage of being suitable for the outdoor welding described above.

Also, in the field butt welding of steel pipe piles, it has been
As described in Japanese Patent No. 85, semi-automatic or automatic welding by the self-shielding arc welding method is often adopted.
At this time, the groove shape of the steel pipe pile welding is rectangular and the groove angle is 15 ~.
It is usual to use a backing metal with a root gap of 4 to 8 mm at 45 degrees. However, the self-shielded arc welding method, as described above, has a shallow penetration depth and the arc is unstable, so that many defects occur especially in the first layer welding,
In addition, there is a problem that welding efficiency is poor due to the large amount of spatter.

According to the present invention of claims 1 to 3, it is possible to perform defect-free, high-efficiency mass welding, deep-penetration fillet welding, etc. by using arc welding to deepen the penetration and suppress the amount of spatter generated. An object of the present invention is to provide an arc welding method and apparatus.

It is another object of the present invention to provide an arc welding apparatus for a steel pipe pile, which can prevent defects and improve efficiency in the field welding of the steel pipe pile.

Another object of the present invention is to provide a flux cored wire suitable for achieving defect-free and highly efficient welding.

[Means for Solving the Problem] The arc welding method according to claim 1 is an arc welding method in which a plurality of wires are simultaneously fed, and each wire is fed by the same feeding motor. , The wires are energized from the same welding power source through the same energizing tip, and the tips of the wires are brought closer during welding in the shielding gas atmosphere to bridge the molten metal at the tips of the wires, One arc is generated between the entangled portion and the mother plate.

The self-shielding arc welding method according to claim 2 is a self-shielding arc welding method in which a plurality of flux cored wires are fed at the same time, and the powder particles constituting the flux are classified into a plurality of types according to the bulk density. Then, each wire containing each kind of powder and granules individually is used as one set, and the tip of each wire is approached during welding to bridge the molten metal at the tip of each wire. One arc is generated between and.

The arc welding apparatus according to claim 3 feeds a plurality of wires to a welding torch at the same time by a wire feeding device, and each wire is energized from the same welding power source through the same energizing tip. The wire feed device and the welding torch each have a power cable, a flexible conduit for wire feed, and a torch cable that integrates a shield gas hose, and each wire that has passed through the current-carrying tip. Of the wire are bridged together so that the weld metal at each wire tip is bridged, and one arc is generated between the bridged part and the mother plate.

The arc welding device for steel pipe piles according to claim 4 is an arc welding device for welding two steel pipe piles by butt-joining each other, along with a ring rail arranged at an end of the steel pipe piles, a torch-mounted carriage and a wire-mounted device. The trolley is run, the trolley with the wire is equipped with multiple wire reels, the trolley with the wire and the trolley with the torch are connected with a flexible conduit, and multiple wires are simultaneously fed to the trolley with the torch via the flexible conduit. In the torch-carrying trolley, the wires passed through the same chip, which are energized by the same power source, are configured such that the wire tips meet each other.

The arc welding apparatus for steel pipe piles according to claim 5 is characterized in that
In the arc welding apparatus for steel pipe piles described in 1 above, a copying device is provided along the surface of the steel pipe in order to keep the distance between the wire tip and the welding point constant.

The steel pipe pile arc welding apparatus according to claim 6 is the arc welding device according to claim 4.
Alternatively, in the arc welding apparatus for a steel pipe pile described in 5, the wire take-out port of the wire-carrying carriage can be set at an arbitrary angle with respect to the torch-carrying carriage.

The flux cored wire according to claim 7 classifies the powder or granules constituting the flux into a plurality of classes according to the bulk density, and uses each wire containing each class of powder or granules individually as one set. It is the one.

[Operation] According to the arc welding method of claim 1, since the molten metal and the slag at each wire tip are bridged with each other to integrate the arc, the droplet is melted from the central portion of the bridge portion. As a result, the droplets migrate toward the pond with a directivity, and as a result, the droplets are concentrated in the molten pool of one pool, the penetration is deep, and the spatter is reduced.

Therefore, the arc welding method according to the first aspect has the following advantages.

In the conventional method, butt multi-layer welding with backing metal in the downward and sideways postures, which was likely to cause slag inclusion and fusion failure, or even in downward and horizontal fillet welding, deep penetration,
Spatter can be reduced and a good weld can be formed.

In addition to a large amount of wire fed at the same time, since spatter loss is small, welding efficiency and welding speed are high, and butt multi-layer welding and fillet welding can be performed with high efficiency.

Since the same feeding motor is used, the feeding speed of each wire can be synchronized and the bridging of the molten metal at the tip of each wire can be stably performed. Further, since the same welding power source and current-carrying tip are used, simplification of equipment can be achieved.

Moreover, the arc welding method according to claim 2, and claim 7.
In the flux cored wire described in (1), the function of the flux in the flux cored wire is to generate shield gas, deoxidize, denitrify, generate slag, and add alloying elements. The flux density was classified into a predetermined range of 2 to 4 steps, and a set of flux cored wires each of which was individually included was manufactured. By feeding these one set of wires at the same time and bridging the molten metal at the tip of each wire into one arc and one pool during welding, there is no defect in the fed flux components and high efficiency. Get the welding method. That is, since a set of flux cored wires each containing powder particles in a bulk density range classified in advance to a predetermined value is used, the flux composition in the wires does not segregate and welding defects do not occur.

The bulk density of the powder and granule components that make up the above flux is 0.5
Since it distributed ~4.5g / cm ^3, which to classify the 2-4 stage, for example, a method such as A~C shown in Table 1.

According to the arc welding apparatus of claim 3, when performing gas shielded arc welding or self-shielded arc welding by using a plurality of wires, the arc welding method of claim 1 can be carried out. As a result, it is possible to provide a semi-automatic welding apparatus that achieves high efficiency and defect-free welding by achieving a large amount of deposition, deep penetration, and suppression of spatter generation. Moreover, since the same welding power source and current-carrying tip are used, the device configuration can be simplified.

Further, according to the arc welding apparatus of claim 3, since the torch cable in which the power cable, the flexible conduit for wire feeding, and the hose for shield gas are integrated is used, the wire feeding apparatus and welding are used. It is possible to simplify the handling of cables with the torch and simplify the device configuration.

According to the arc welding apparatus for a steel pipe pile described in claim 4, the on-site welding of the steel pipe pile can be performed by the arc welding method according to the above-mentioned claim 1, and as a result, defects can be prevented and efficiency can be improved.

According to the arc welding apparatus for a steel pipe pile of the fifth aspect, it is possible to keep the distance between the wire tip and the welding point constant and prevent defects in the steel pipe pile that is not necessarily a perfect circle.

According to the arc welding apparatus for a steel pipe pile of claim 6, since the wire outlet of the wire-carrying trolley can take an arbitrary angle with respect to the torch-carrying trolley, the wire is gentle even if the pile diameter of the steel pipe pile changes. It can be delivered smoothly with a smooth curve.

[Embodiment] (Embodiment 1) In the arc welding apparatus shown in FIG. 1, 1 is a mother board, 2 is an energizing tip, 3 is a wire feeding motor, 4 is a wire, 5 is a controller, and 6 is a welding power source. , 7 are wire passage holes, and 8 is a conduit cable or nozzle.

In this arc welding device, in consumable electrode type arc welding using three wires 4, the tips of each of the three wires 4 passing through the tip 2 meet at one point at a certain distance from the tip of the feeding tip 2. As described above, the power feeding chip 2 is provided with a plurality of wire passage holes 7 at an angle with respect to the chip axis, and the wires 4 are simultaneously fed to the wire passage holes 7 by the feeding motor 3 through the conduit cable 8. In addition, arc welding is performed by supplying electricity from the same power source 6 via the control device 5.

According to this arc welding apparatus, the penetration is deeper, the bead shape is better, and the spatter is reduced as compared with the 1-wire arc welding method.

The reason for this is as follows. That is, in the multi-wire method, when the molten metal at the tip of the wire being welded is bridged, a single arc is generated, so that the current density is 1
-It becomes much larger than the wire method, and the droplets move from the center of the bridging portion toward the molten pool in a directional manner. Therefore, the molten pool is vigorously stirred, the penetration shape is increased in both width and depth, and the bead shape is improved. Further, since the directivity of the arc is strong, spatter is reduced.

By using this multi-wire method, it is possible to perform butt multi-layer welding with a backing plate in downward and sideways postures and high-efficiency welding with a large welding amount in downward and horizontal fillet welding.

1 is similar in appearance to that described in Japanese Patent Laid-Open No. 62-197279, but in the present invention, the wire passage hole provided in the chip intersects with the axis of the chip. The arc to be generated is decisively different from that of the conventional example. That is, in the present invention, a plurality of wire tip molten metals are bridged to generate a single arc between the portions and the mother plate, whereas in the conventional example, the same number of arcs as the wires are generated. Therefore, by providing a wire passage hole having an angle on the axis of the tip, an arc welding method which is essentially different from the conventional example can be realized.

(Embodiment 2) In the gas shielded arc welding apparatus of FIG. 2, 1 is a mother board, 2 is an energizing tip, 3 is a wire feeding motor, 4 is a wire, 5 is a controller, 6 is a welding power source, and 7 is a welding power source. Is a wire passage hole, 8 is a conduit cable or nozzle, and 9 is a gas introduction pipe.

In this welding apparatus, the two wires 4 are fed by the feeding motor 3 through the nozzle 8 into the passage hole 7 of the chip 2. The wire passage holes 7 are each inclined by 2.9 degrees with respect to the axis of the chip so that the wires 4 meet at the position of 25 mm from the tip of the chip 2 (see FIG. 3). Electric power is supplied to the wire 4 by the same welding power source 6 via the control device 5. Further, the shield gas is supplied to the nozzle 8 through the gas introduction pipe 9. as a result,
The molten metal at the ends of the two wires bridges together, creating a single arc between the bridge and the mother plate.

As shown in Table 5, the effect of this 2-wire gas shielded arc welding method using a wire of 1.6 mm diameter is deeper than that of the conventional 1-wire gas shielded arc welding method. That is, the generation amount is small and a good bead is formed at the time of high current welding regardless of the welding speed.

In this example, the wire passage hole has a certain angle, but most of the length of the hole may be parallel to the axis of the chip, and only the hole near the tip of the chip may have a certain angle.

(Embodiment 3) In the self-shielding arc welding apparatus shown in FIG. 4, 1 is a mother plate, 2 is an energizing tip, 4 is a wire, 10 is a bridging portion of a wire tip molten metal, 11 is an arc and a droplet, 12 Is the molten pool, 13
Is weld metal. The bulk density range of the powder or granular material forming each wire 4 is as shown in B of Table 1, for example.

That is, in this self-shielded arc welding device, the composition for shield gas generation and slag generation and the composition for deoxidation and denitrification are separated in the function of the flux in the flux cored wire. A pair of wires contained individually are used. A 3-wire self-shielded arc welding method is used in which these are fed at the same speed by one motor at the same time, and the current is supplied from the same welding power source through the same tip. The gap at the tip of the wire where the arc is generated during welding. Was 10 mm or less, and one arc was used to make the molten pool into one pool to deepen the penetration and reduce the spatter.

As a result, the conventional 1-wire self-shielded arc welding method (comparative method) could not be applied due to the occurrence of slag entrainment. Butt and multi-layer welding with backing metal in down and sideways positions and down and horizontal fillets. By the method of the present invention, welding can be performed without defects and with high efficiency.

Since a normal flux cored wire is manufactured so that the flux composition is not biased, a wire intentionally segregated with a deoxidizing / denitrifying agent was manufactured in the comparative method. Table 2
As shown in FIG. 5, in the method of the present invention, the leading wire was made to contain the deoxidizing / denitrifying agent, and the trailing wire was made to contain the shielding gas generating / slag forming agent. As a result, in the method of the present invention, stable welding can be performed without slag entrainment and other defects, whereas in the comparative method using the trial wire, blowholes occurred.

The reasons for the effectiveness of the present invention found in Example 3 are as follows. First, in the flux function, the bulk densities of various compositions for shielding gas generation and slag generation and those of various compositions for deoxidation / denitrification differ, so these are mixed at the same time. If it is included in the wire, there is a risk of composition deviation. In order to avoid these, by using a set of wires that separately contain fluxes with function sharing under the condition that one arc and one pool are obtained, it is possible to more reliably obtain a defect-free weld. . Next, in the 3-wire self-shielded arc welding method, the distance between the wire tips during welding is adjusted.
Since it was 10 mm or less, the molten metal and slag bridged the ends of both wires, and the arc became one, and the droplet moved from the center of the bridge toward the molten pool in a directional manner. As a result, the penetration was deep and the spatter was reduced.

Example 4 A comparative method using a wire in which a deoxidizing / denitrifying agent was intentionally segregated was compared with the method of the present invention composed of a combination of four wires. Table 3 shows the contents of each wire, and Table 4 compares the welding results. In the method of the present invention, the above-mentioned set of wires is simultaneously fed by one motor at the same speed, and the current is supplied from the same welding power source through the same tip as the self-shield welding method. During welding, the molten metal at the tip of each wire was bridged to form one arc and one pool. According to Table 4, it was recognized that the method of the present invention enables stable welding without slag inclusion and other defects. On the other hand, blowholes were generated in the comparative method using the trial wire.

(Example 5) In the gas shield arc welding apparatus of FIG. 5, 1 is a mother plate, 2A is a welding apparatus, 3 is a wire feeder, 4 is a wire,
Reference numeral 5 is a control device, 6 is a welding power source, and 8 is a torch cable. 4A is a wire reel, 6A is a power cable, 11
Is an arc.

This gas shielded arc welding device includes a wire feeding device 3
Welding torch of two wires 4 simultaneously by a single motor
2A, and each wire is energized from the same welding power source 6 through the same energizing tip. Furthermore, this gas shielded arc welding device is equipped with a welding torch 2A.
The tips of the wires 4 that have passed through the passage holes provided in the current-carrying tip 2 are guided so as to be associated with each other, and the molten metal at the tips of the wires is bridged to form one arc between the bridge and the mother plate 1. It is a semi-automatic welding device that realizes the generation of.
The passage hole of the current-carrying tip is the passage hole 7 shown in FIG.
Similarly, the wire 4 has an inclination of 2.9 degrees with respect to the axis of the chip so that the wire 4 will meet at a position of 25 mm from the tip of the chip 2.

According to this gas shielded arc welding device, 2
By bridging the molten metal at the tip of the wire 4 and generating one arc between the bridging portion and the mother plate 1,
It is possible to achieve deep penetration, increase the amount of welding, and suppress spatter, and realize welding with higher efficiency than the current gas shield welding.

In addition, in this gas shield arc welding device, a power cable is provided between the wire feeding device 3 and the welding torch 2A.
A torch cable 8 in which 6A, a flexible conduit 4A for wire feeding, and a hose 101 for shield gas are integrated with an outer cover 102 is extended (see FIG. 6). This simplifies the handling of cables between the wire feeding device 3 and the welding torch 2A and simplifies the device configuration.

Table 6 shows the results of comparison of the deposition rate when performing CO ₂ gas shielded arc welding and self-shielded arc welding using the apparatus according to the present invention with that of the conventional method (1-wire method, respectively). According to Table 6, it is recognized that the arc welding apparatus of the present invention can achieve high welding efficiency.

(Embodiment 6) FIGS. 7 to 9 show a self-shielding gas arc welding apparatus for butt welding two steel pipe piles 20. In this welding device, two traveling carriages are installed on a ring rail 21 attached near the lower end of the upper steel pipe pile 20, one torch-carrying carriage 22 on the drive side and another one on the driven side A dolly 23 is used, and both dollies 22 and 23 are connected by a towing connecting bar 24. Both carriages
For traveling 22 and 23, the torch-equipped carriage 22 is provided with a gear 26 that meshes with a rack 25 provided on the ring rail 21, and this is provided with a variable speed motor 27.
By rotating with.

The torch-equipped carriage 22 includes a control box 28 for controlling current, voltage, and speed, and a welding torch 29. The welding torch 29 is attached to the carriage 22 via a torch holding device 30 so that the welding torch 29 can take various postures with respect to the welding line. The function of the torch holding device 30 is to rotate the torch 29 so that it has an advancing angle and a receding angle with respect to the welding line.
29 vertical movement function, rotating function and torch that allows the torch 29 to take various angles in a plane perpendicular to the welding line
29 are four functions that allow the steel pipe pile 20 to move in and out in the radial direction.

Furthermore, since the steel pipe pile 20 is not necessarily a perfect circle, the torch 29
When the tip of the torch 29 moves in a concentric circle with the ring rail 21, the distance between the welding line in the groove of the steel pipe and the tip of the torch 29 constantly fluctuates, and leaving it to cause welding defects.
Therefore, in order to keep this distance constant, a torch holding device
30 is a slide device 3 equipped with wheels 31 that follow the surface of the steel pipe pile.
2, and a spring 33 for bringing the wheel 31 of the slide device 32 into contact with the surface of the steel pipe pile, and is supported by the torch-mounted cart 22.

34 is an angle slide arm, 35 is a vertical slide, 36
Are front and rear slides.

Next, the wire-carrying carriage 23 is provided with a wire feeding device 37 and two wire reels 38, and the feeding device 37 has a variable speed motor 39, a pair of upper and lower feeding rollers 40, and a wire. It consists of a bend straightener.

Further, a flexible conduit cable 42 for guiding the two wires 41 is extended between the welding torch 29 and the wire feeding device 37.

Further, the face plate 43 to which the wire feeding device 37 and the wire reel 38 are attached is a movable type that can take an arbitrary angle with respect to the base of the wire-mounted carriage 23, and the conduit cable can be used even if the diameter of the target steel pipe pile changes. 42 has a gentle curve.

Then, in this welding device, the wire feeding device 37
Thus, the wires 41 of both wire reels 38 are simultaneously fed to the torch-mounted carriage 22 through the conduit cable 42, and each wire 41 passed through the same chip of the torch 29 that is energized with the same power source in the torch-mounted carriage 22, The tips of the wires 41 are configured to be associated with each other. This allows each wire 41
The molten metal at the tip of is bridging, and one arc is generated between this bridging portion and the mother plate.

Therefore, according to this welding apparatus, the arc welding method of the present invention can be carried out in the field welding of the steel pipe pile 20, and as a result, defects can be prevented and the efficiency can be improved.

Further, according to this welding device, the distance between the tip of the wire 41 and the welding line can be kept constant, and defects can be prevented for steel pipe piles that are not necessarily perfect circles.

Further, with this welding device, the wire outlet of the wire-carrying carriage 23 can take an arbitrary angle with respect to the torch-carrying carriage 22, so that the wire 41 has a gentle curve even if the pile diameter of the steel pipe pile 20 changes. It can be drawn and delivered smoothly.

Tables 7 and 8 show the results when this welding apparatus is applied to welding steel pipe piles having a plate thickness of 25 mm and a diameter of 1,600 mm in comparison with 1-wire self-shield welding. According to Tables 7 and 8, it is recognized that the implementation of the present invention can prevent defects and improve efficiency in the field welding of steel pipe piles.

[Advantages of the Invention] According to the arc welding method and apparatus of the present invention as set forth in claims 1 to 3, by using arc welding, the depth of penetration is deep and the spatter generation amount is suppressed, so that a defect-free and highly efficient multilayer structure can be obtained. Welding and deep penetration fillet welding can be performed.

According to the arc welding apparatus for steel pipe piles of claims 4 to 6 of the present invention, defects can be prevented and efficiency can be improved during on-site welding of the steel pipe piles.

According to the flux cored wire of the present invention of claim 7, it is possible to provide a flux cored wire suitable for realizing defect-free and highly efficient welding.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an arc welding device, FIG. 2 is a schematic diagram showing a gas shield arc welding device, FIG. 3 is a perspective view showing a current-carrying tip, and FIG. 4 is a schematic diagram showing a self-shield arc welding device. Fig. 5, Fig. 5 is a schematic diagram showing a gas shielded arc welding device, Fig. 6 is a sectional view showing a torch cable, Fig. 7 is a schematic diagram showing an arc welding device for steel pipe piles, and Fig. 8 is a schematic diagram showing Fig. 7. FIG. 9 is a front view of an essential part and FIG. 9 is a plan view of the essential part of FIG. 2 ... energizing tip, 3 ... wire feeding motor, 4 ...
Wires, 5 ... Control device, 6 ... Welding power source, 7 ... Wire passage hole, 8 ... Conduit cable, 20 ... Steel pipe pile, 21 ... Ring rail, 22 ... Torch carrier, 23 ... Wire-carried trolley, 29 ... Welding torch, 30 ... Torch holding device, 37 ... Wire feeding device, 38 ... Wire reel, 42 ...
… Conduit cable.

Claims (7)

[Claims] 1. In an arc welding method in which a plurality of wires are simultaneously fed, each wire is fed by the same feeding motor and each wire is energized from the same welding power source. Through welding, the tip of each wire is approached during welding in a shield gas atmosphere to bridge the molten metal at the tip of each wire, and one arc is generated between the bridging part and the mother plate. An arc welding method characterized in that 2. A self-shielding arc welding method in which a plurality of flux cored wires are fed at the same time, and the powder particles constituting the flux are classified into a plurality of groups according to the bulk density, and the powder particles of each group are classified. Each wire including the body alone is used as one set, and the tip of each wire is approached during welding to bridge the molten metal at each wire tip, and one arc is provided between the bridge and the mother plate. A self-shielding arc welding method, which comprises: 3. An arc welding device in which a plurality of wires are simultaneously fed to a welding torch by a wire feeding device and each wire is energized from the same welding power source through the same energizing tip. Between the feeder and the welding torch,
A torch cable that integrates a power cable, a flexible conduit for wire feeding, and a hose for shield gas is extended, and the tips of the wires that have passed through the current-carrying tip are guided so as to meet each other. An arc welding device configured to bridge molten metal and generate one arc between the bridge and the mother plate. 4. An arc welding apparatus for welding two steel pipe piles by abutting each other, wherein a torch-mounted carriage and a wire-mounted carriage are run along an annular rail arranged at an end of the steel pipe piles,
Equipped with multiple wire reels on the wire-carrying carriage, the wire-carrying carriage and the torch-carrying carriage are connected by a flexible conduit, and multiple wires are simultaneously sent to the torch-carrying carriage through the flexible conduit. An arc welding apparatus for steel pipe piles, characterized in that the wires are passed through the same chip and are energized by the same power source, and the ends of the wires are associated with each other. 5. The arc welding device for a steel pipe pile according to claim 4, further comprising a copying device along the surface of the steel pipe to make the distance between the tip of the wire and the welding point constant. 6. The wire take-out port of the wire-carrying carriage can be set at an arbitrary angle with respect to the torch-carrying carriage.
Or the arc welding apparatus for steel pipe piles according to 5. 7. A flux cored wire, wherein powder particles constituting a flux are classified into a plurality of classes according to their bulk densities, and each wire containing each class of powder particles is used as one set.