JP3121597B2 - 2-electrode single-sided gas shielded arc welding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for one-sided gas shielded arc welding of a groove formed of a material to be welded. The present invention also relates to a highly efficient single-sided gas shielded arc welding capable of obtaining high toughness.

[0002]

2. Description of the Related Art In recent years, in the construction of various welded structures,
The application of the gas shielded arc welding method is rapidly increasing in various fields because the welding cost can be reduced and the efficiency can be improved. In particular, the application in fields such as shipbuilding and bridges where the ratio of butt welding is high is remarkable. However, from the viewpoint of reducing the total cost of welding, increasing the speed of short to long single-sided welding has become a major issue.

[0003] As a single-sided welding method, a submerged arc welding method has been actively studied as a board joint welding for shipbuilding. For example, the submerged arc welding method disclosed in Japanese Patent Publication No. 60-59072 discloses a method for preventing a decrease in the penetration depth of a weld bead and a deterioration in the external appearance of a bead due to the oscillation of an electrode.
The prevention of cracks in the first layer bead is also to be realized. However, this submerged arc welding method requires a large amount of equipment to be used, and has a problem that short-length welding is complicated and cannot be applied.

A gas shield downward welding method using a flux-cored wire and having a high current density, which is disclosed in Japanese Patent Publication No. 61-49027, uses a thin composite wire and increases the wire protrusion length. The efficiency of downward welding at a high welding speed with a large current is high, and the welding cost is reduced. However, since the protruding length of the wire is as long as 35 to 70 mm, there are problems such as poor shielding, misalignment of the target position due to the wire being bent, and cracks in the first layer bead during single-sided welding.

Japanese Patent Publication No. Sho 50-7543 discloses that an appropriate amount of steel grains or iron powder is filled in a groove contacted with a backing material, and welding is performed while oscillating a small diameter wire. I have. However, in this method, good welding cannot be performed unless a groove gap is provided, and the groove angle is large.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the welding workability, crack resistance and back bead of single-sided welding of short to long welding structures to obtain a sound and high-toughness weld. As a first object, and a second object is to easily and efficiently increase a sheet joining operation efficiency.

[0007]

(1) A welding apparatus according to the present invention is a two-electrode single-sided gas shielded arc welding apparatus. The welding equipment (WL, WR) has a Y or a groove angle of 30 to 55 °. V
Backing material (BP) applied to the back of the groove (Wo) of the shape, the groove (Wo)
o) a steel grain or iron powder to be filled inside, a bogie (1) running in the direction (y) in which the groove (Wo) extends, and the bogie arranged in the direction (y) in which the groove (Wo) extends. Two single-sided gas shielded arc welding torches (Tf, T) mounted on (1) and facing the groove (Wo)
b), a torch oscillating mechanism (6f, 6b) for oscillating the two welding torches (Tf, Tb), and the two welding torches (Tf, Tb).
b) at least one of the torch angle adjusting mechanisms (80f, 80) for adjusting the inclination (γ) with respect to the direction (y) in which the groove extends.
b), and a upstream side with respect to the running direction of the carriage (1)
The welding electrode wire of the preceding welding torch (Tf) is a solid wire.
Ear, welding electrode wire for the downstream welding torch (Tb) on the downstream side
Ya Ru Oh in the flux-cored wire.

[0008] In order to facilitate understanding, in the parentheses, reference numerals corresponding to corresponding elements, corresponding items or equivalents of the embodiment shown in the drawings and described later are added for reference.

[0009] According to this, welding can be performed with high efficiency in which the arc is stable, crack resistance and good front and back beads can be obtained.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (2) A rail (r) supported on the cart (1) and installed on a workpiece (WL, WR) substantially parallel to the groove (Wo). The rotatable rollers (3f, 3
b) is further provided. With this roller (3f, 3b), the truck (1)
Are guided along the rail (r). (3) The welding electrode wires of the two welding torches (Tf, Tb)
The distance between the electrodes (9b) (FIG. 6) is not less than 100 mm and not more than 600 mm. 1
If it is less than 00 mm, the arc becomes unstable and the back bead becomes too large, and if it exceeds 600 mm, the toughness is improved, but the size of the device is undesirably large. (4) Of the two welding torches (Tf, Tb), a trailing welding torch (Tb) that is downstream with respect to the traveling direction of the bogie.
Of the welding electrode wire (9b)
TiO ₂ : 2.5% or more and 7.0% or less ZrO ₂ : 0.4% or more and 1.0% or less Al ₂ O ₂ : 0.1% or more and 1.0% or less Si: 0.2% or more and 1.2% or less Mn: 1.0% or more and 4.0% or less Mg: 0.1 % Or more and 1.0% or less, and the total of one or two of Na and K
A flux-cored wire filled with a flux of not less than 0.03% and not more than 0.3%. According to this, there is toughness,
There is no slag involved, no pits or blow holes,
It is possible to realize welding in which a good bead shape is obtained.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0012]

1 to 3 show one embodiment of the present invention. FIG.
3 to 3, work pieces WL and WR, which are thick plates, are arranged on the left and right sides (FIG. 2), and a V-shaped groove extending in the y direction is formed at the upper part. The welding device A is provided in the width direction x of the groove.
Is welded in the y-direction along the rail r with the center position (Wo) of the target as the target position for welding. The welding device A has two leading welding torches Tf and Tb mounted on the carriage 1 in a state of being arranged in the y direction. The welding machine A holds the carriage 1 by performing welding on both welding torches. By traveling in the same direction, a two-stage weld bead can be realized in one travel.

A rail r extending in the y direction along a groove is previously laid on the upper surface of the left work (WL). Slotted rollers 3f and 3b (FIG. 1) for receiving the rail r in the forward and rearward directions are rotatably mounted on the support plate 13 (FIG. 2) on the left side of the bogie 1 of the welding apparatus A. And guide the carriage 1 in the y direction along the rail r. The trolley 1 of the welding device A is further equipped with a leading sensor Sf and a trailing sensor Sb (FIG. 1) arranged side by side in the y direction and supported by the leading and trailing sensor oscillating mechanisms 5f and 5b, respectively. And is oscillated in the left-right direction (the direction across the groove). The preceding welding torch Tf is supported by the preceding torch oscillating mechanism 6f and is oscillated in the left-right direction. The following welding torch Tb is supported by the following torch oscillating mechanism 6b and is oscillated in the left-right direction.

FIG. 2 is a trolley 1 shown in FIG.
5 shows a longitudinal section of a sensor oscillation mechanism 5f. A front wheel shaft 21 to which wheels 2fR and 2fL are fixed is provided at the lower part of the bogie in the traveling direction, and is rotatably supported by the bogie frame 11. Sprocket wheels 22, 24 are fixed to the front wheel shaft 21. A bogie drive motor M1 is fixedly supported on the bogie frame 11, and a drive sprocket wheel is fixedly mounted on a rotating shaft of the bogie drive motor M1.
Is bound to. Further, behind the bogie frame, it extends in the x direction (not shown), and the right rear wheel 2bR and the left rear wheel are fixedly supported at both ends, and a rear wheel shaft to which a driven sprocket wheel is integrally fixed is rotatably supported. Have been. This driven sprocket wheel and a driven chain of the aforementioned sprocket wheel 24 of the front wheel shaft 21 are connected to each other, and transmit the rotation of the front wheel shaft 21 to the rear wheel shaft.

When the motor M1 is forwardly energized, the front wheel shaft 21 and the rear wheel shaft rotate with the rotation of the rotating shaft, and the front and rear four wheels simultaneously rotate.
Moves forward. Since the grooved rollers 3f and 3b are guided by the rail r, the carriage 1 advances in the y direction along the rail r. When the motor M1 is reversely energized, the carriage 1 moves backward (or reverse) in the y direction.

The upper portion of the carriage 1 has a switch for instructing the carriage 1 to move forward / reverse, a switch for instructing each of the torches Tf and Tb to move up and down, and a switch for instructing the start / stop of welding. Frame 7 supporting operation end 9f
There is. The hand-operated end 9f can be detached from the frame 7, and in this embodiment, the hand-operated end 9f is detached from the frame 7, so that the hand-operated end 9f is shown in FIG. 7 is indicated by a two-dot chain line.

The carriage 1 has a preceding sensor oscillation mechanism 5
f is attached. The frame 51 of the sensor oscillation mechanism 5f is fixed to the carriage 1, and inside the frame 51 is a sensor oscillation motor M5f, the rotation axis of which extends rightward, extends in the x direction, and is rotatable. It is connected to the left end of the supported screw rod 52. Motor M5f
The screw rod 52 is driven to rotate along with the rotation shaft. A slider 54 is screwed to the screw rod 52, and the slider 5
Reference numeral 4 denotes a guide rail 53 laid in the x direction on the bottom surface of the frame 51, and is guided to be unrotatable, forward and backward in the x direction. When the motor M5f rotates forward, the screw rod 52 rotates, and the slider 54 is guided by the guide rail 53 and moves in the x direction (right direction). When the motor M5f rotates in the reverse direction,
The slider 54 moves to the left.

A support rod 55f extending in the x direction and projecting from the right side of the frame 51 is fixed to the right end of the slider 54. The upper end of the arm 41 is fixed to the tip of the support rod 55f, and the arm 42 extending in the y direction is fixed to the lower end. The arms 41 and 42 are connected in an inverted T-shape. On the right side of the arm 42, there is a cylindrical pin protruding rightward, and a support arm 43 is attached to this pin.
It is fixed with a thumb screw 44. The preceding sensor Sf is a conductor wire, passes through a through hole at the tip of the support arm 43, and is fixed to the support arm 43 with a thumb screw 45. By loosening the thumbscrew 44 and rotating the support arm 43 with respect to the pin 44, the angle of the preceding sensor Sf with respect to the z-axis can be adjusted, and the thumbscrew 45 can be loosened to raise the preceding sensor Sf. , The depth of the leading edge of the preceding sensor Sf with respect to the groove can be adjusted. When replacing or repairing the preceding sensor Sf (deleting the attached spatter), the thumb screw 45 may be loosened to extract the preceding sensor Sf.

The preceding sensor Sf includes a conductor wire, a support
The drums 43 and 41 and the support rod 55f are conductors (steel material), and the support rod 55f is fixed to the slider 54 via an insulator. That is, the leading sensor Sf, the supporting arm 4
3, 41 and the support rod 55f are electrically continuous with each other, and are insulated from the slider 54 and the frame 51 which are the equipment ground level. That is, it electrically floats from the equipment ground. An electric lead is connected to the support rod 55f in the frame 51, and this electric lead is connected to a contact detection circuit 110 shown in FIG.

The base plate of the preceding torch oscillating mechanism 6f is fixed to the frame 51 of the preceding sensor oscillating mechanism 5f. The torch oscillating mechanism 6f includes an electric torch height adjusting mechanism for driving the support arm 81 up and down,
This torch height adjusting mechanism is supported, and is supported by a supporting arm 8.
1 includes an electric oscillating mechanism for oscillating (oscillating) driving in the extending x direction. The supporting arm is driven up and down in response to an instruction to move the operator up and down. Automatically drives the supporting arm 81 in the x direction (oscillating drive, that is, reciprocating reciprocating drive).

The support arm 81 has a torch support mechanism 80f.
, The preceding welding torch Tf is supported. The support arm 81 has a scale indicating the amount of movement of the preceding welding torch Tf in the x direction.

Referring to FIG. 1 and FIG. 2, the torch support mechanism 80f is provided with a support plate 82 having a substantially inverted isosceles triangle.
And a rotatable disk 83 rotatably supported by a pin 86 on the support disk 82 and rotating with respect to the support disk 82 around the pin 86 in parallel with the yz plane.
And a torch holding member 87 fixed by The support board 82 is fixed to the right end of the support arm 81 with a screw 81a. At the upper part of the support plate 82, there is provided a guide groove defining an arc centered on a round hole formed at the lower end thereof, and guides a set screw 84 inserted from the left surface of the support plate 82. The turntable 83 has a rectangular shape that is long in the z-direction.
A round hole for guiding the pin 86 is open. A pin 86 is inserted into a hole formed in the lower end of the turntable 83 and the lower end of the support board 82.
To be rotatably supported with respect to the lower end. A screw hole is formed in the upper part of the turntable 83, and the right end of a set screw 84 protruding through the guide groove of the support plate 82 is screwed. By tightening the set screw 84, the turntable 83 comes into close contact with the support board 82 and is fixed.

The operator loosens the set screw 84 and turns the turntable 8
3 with the pin 86 as a reference, the set screw 84 from the reference position.
Is rotated within a range guided by the guide groove of the support board 82 (15 ° from the reference position), and the set screw 84 is tightened at a required angle to fix the turntable 83 to the support board 82. Turntable 8
A torch holding member 87 supporting the preceding welding torch Tf is fixed to 3 by a screw 85, and the leading welding torch Tf can rotate the tip thereof with the rotation of the turntable 83. Thereby, the angle of the torch Tf with respect to the z-axis (the inclination γ toward the forward side and the backward side in the y direction) can be adjusted.

The mechanism (4b, 5b, 6b, 80b) for oscillating the trailing torch Tb and the trailing sensor Sb and the support structure on the carriage 1 are composed of the mechanism (4f, 5f) of the preceding welding torch Tf and the preceding sensor Sf. , 6f, 80f), and a detailed description thereof will be omitted.

FIG. 3 shows a system configuration for oscillating the preceding welding torch Tf and the preceding sensor Sf. The system configuration for oscillating the trailing torch Tb and the trailing sensor Sb is the same as that described above, so that the illustration of the system is omitted. However, the control circuit 200 in FIG. 3 is shared by a system for oscillating the preceding welding torch Tf and the preceding sensor Sf and a system for oscillating the following torch Tb and the following sensor Sb.

The contact detection circuit 110 is connected to a support rod 55f, and the support rod 55f and the support arms 43, 4
An electrically continuous electric lead is connected to the preceding sensor Sf via 1 and is electrically floating from the equipment ground level. The contact detection circuit 110 applies a constant voltage to the electric lead via a resistor, and when the preceding sensor Sf is not in contact with either the work WL or WR, the electric lead is When the preceding sensor Sf comes into contact with either the work WL or WR, the potential of the constant voltage (high level H) is set to the equipment earth level (low level L).
The contact detection circuit 110 supplies a binary signal representing the contact (low level L) and the non-contact (high level H) to the control circuit 200. When the binary signal switches from the high level H to the low level L while driving the preceding sensor Sf to the right, the control circuit 200 determines that the preceding sensor Sf has contacted the work WR, and determines that the preceding sensor Sf has contacted the work WR. When the binary signal is switched from the high level H to the low level L while the left sensor is driven to the left, it is determined that the preceding sensor Sf has contacted the work WL.

The preceding sensor Sf is oscillated in the vertical direction x (horizontal direction) with respect to the extending direction y of the groove via the sensor oscillating mechanism 5f. The sensor oscillation motor M5f of the sensor oscillation mechanism 5f is a stepping motor, and the rotation direction and the amount of rotation (the number of steps) are controlled by the control circuit 200 via the motor driver MDf1. When the control circuit 200 instructs the driver MDf1 to perform forward rotation of the motor M5f, the driver MDf1 outputs a forward rotation pulse voltage of a predetermined cycle to the motor M5f.
5f, whereby the motor M5f rotates stepwise (forward) and the preceding sensor Sf moves rightward. Conversely,
When the control circuit 200 instructs the driver MDf1 to perform reverse rotation of the motor M5f, the driver MDf1 applies a reverse rotation pulse voltage of a predetermined cycle to the motor M5f, and thereby the motor M5f is driven.
5f rotates stepwise (reverse rotation), and the preceding sensor Sf moves to the left. While the control circuit 200 is supplying the driver MDf1 with the forward rotation instruction signal or the reverse rotation instruction signal, the driver MD
f1 continuously applies a rotation drive pulse voltage of a predetermined period to the motor M5f, and the motor M5f continues to rotate.

On the other hand, the preceding welding torch Tf is oscillated in the vertical direction x (horizontal direction) with respect to the extending direction y of the groove via the above-described to-thiosylate mechanism 6f. The oscillating motor M7f of the trithiosylate mechanism 6f is a stepping motor, and the rotation direction and the amount of rotation (the number of steps) are controlled by the control circuit 200 via the motor driver MDf2. When the control circuit 200 instructs the driver MDf2 to perform forward rotation of the motor M7f, the driver MDf2 applies a forward rotation pulse voltage of a predetermined cycle to the motor M7f, whereby the motor M7f rotates stepwise (forward) to perform a preceding rotation. H moves to the right. Conversely, when the control circuit 200 instructs the driver MDf2 to rotate the motor M7f in reverse, the driver MDf2 applies a reverse rotation pulse voltage of a predetermined cycle to the motor M7f.
Rotates stepwise (reverse), and the preceding torch Tf moves to the left. While the control circuit 200 is supplying the forward rotation instruction signal or the reverse rotation instruction signal to the driver MDf2,
Continuously supplies a rotation drive pulse voltage of a predetermined period to the motor M7f, and the motor M7f continues to rotate.

The control circuit 200 drives the sensors Sf and Sb in a reciprocating scanning drive (oscillation drive) in the x direction at a period inversely proportional to the welding speed (y direction), and the torch set by the operator before the start of welding. The right and left of the position (x direction) are centered on the oscillation width set by the operator, and the change in the groove center position and the oscillation width obtained by the oscillation of the sensor. Shift the center in the x direction. That is, the operator performs a to-situ oscillation of the width set by the operator on the operation panel OB, and shifts the center of the oscillation in the same direction by the change in the x direction of the groove center position obtained by the oscillation of the sensor. I do.

The operator inputs the oscillation width and welding conditions (welding speed, welding current value, etc.) to the control circuit 200 via the operation panel 0B. Dolly 1 on Work WL
The operator adjusts the y position, the height of the torch relative to the work (z position adjustment), the x position adjustment of the torch, and the x position adjustment of the sensor by operating a switch of the hand-held operating end 9f. Do.

Double shields 100f and 100b are attached to the respective tips of the welding torches Tf and Tb. FIG. 4 shows an enlarged vertical section of the double shield 100b attached to the welding torch Tb. The welding torch Tb feeds the welding wire 9b into the groove from the welding tip WC at the tip and blows out the shielding gas.
A double shield 100b is mounted on the welding torch Tb. The double shield 100b includes an attachment 101 fixed to the welding torch Tb,
01 and the inner nozzle 102 fixed to the outer nozzle 1
03 is included. The inner nozzle 102 surrounds the welding tip WC and guides a shield gas (first shield gas) blown out from the welding torch Tb downward along the tip WC. The first shield gas blows out from the lower end opening of the inner nozzle 102 to the periphery of the welding wire 9b exposed to the outside of the tip WC. The outer nozzle 103 has a lower half expanded in a conical cylindrical shape, and the outer nozzle 103 is provided with a welding torch Tb.
A second shield gas G is supplied from the outside of the nozzle, and is blown out of the first shield gas from the lower end opening along the outer peripheral surface of the inner nozzle 103. The molten portion immediately below the welding wire 9b is doubly shielded by the first shield gas and the second shield gas. Hereinafter, a mode in which the second shield gas is blown out in addition to the first shield gas is referred to as a "double shield", and a mode in which only the first shield gas is blown is "no double shield". Or, it is called "single shield."
The structure of the double shield 100f is the same as the structure of 100b.

The groove formed by the work WR, WL (material to be welded) has a V or Y shape (FIG. 3) having a groove angle of 30 to 55 ° so that the groove does not shift during welding. It is preferable to temporarily attach the groove inner surface by tack welding. A backing material BP is applied to the back surface of the groove, and steel grains or iron powder is scattered in the groove at a height of 1/4 or more and 2/3 or less of the plate thickness, and the preceding welding electrode wire 9f (Torch) Tf) is given a swing of 40 times / minute or more and 150 times / minute or less, and the subsequent welding electrode wire 9b (torch Tb) is given a swing of 30 times / minute or more and 120 times / minute or less. One unit of the swing, ie, one time, is one reciprocation. The welding current density of the preceding welding electrode wire 9f is 230 A / mm ² or more per wire cross-sectional area, and the welding current density of the succeeding welding electrode wire 9b is 150 A / mm ² or more per wire cross-sectional area. The distance Dw between the poles of 9f and 9b should be 100mm or more and 600mm
By performing two-electrode single-sided gas shielded arc welding as described below, the arc is stabilized, cracking resistance and good front and back beads can be obtained, and highly efficient welding can be performed. As shown in FIG. 6, the inter-electrode distance Dw is the distance between the leading welding electrode wire 9f and the trailing welding electrode wire 9b along the groove of the work.

FIG. 5 shows the relationship between the spray height of steel grains and the shape of the back bead in two-electrode single-sided gas shielded arc welding of several plate thicknesses. Table 1 shows the welding conditions at that time. In the experiment, the current and swing width (oscillating
Width) and the number of swings (the number of oscillations; times / minute). The "root gap" in Table 1 means the shortest distance between the opposed works WR and WL in the groove cross section. FIG. 3 shows the root gap.

[0034]

[Table 1]

It should be noted that a circle symbol, a triangle symbol, and an X in FIG.
The symbol indicates the measurement point, the circle symbol indicates that the back bead shape is good, the triangle symbol indicates that the back bead shape is bad, and the X symbol indicates that the back bead shape is bad or burn-through has occurred.

FIG. 5 shows that the steel grains were inserted into the groove of each thickness.
By spreading and welding to a height of 1/4 or more and 2/3 or less,
It turns out that a back bead shape becomes favorable. If the spray height exceeds 2/3 of the plate thickness, the back bead shape is bad or the back bead is not formed. If it was less than 1/4, burn-through occurred.

The particle size distribution of the steel grains or iron powder is as follows.
It is preferable that the diameter be 5 mm or less from the viewpoint of improving the stability of the arc and the shape of the back bead. The component is mainly composed of Fe, but C is preferably 0.10% or less, S and P are preferably 0.020% or less from the viewpoint of cracking resistance, and the other components are Si, Mn, and Mo in consideration of the strength and toughness of the weld metal. May also contain a deoxidizing agent or an alloying agent. Granules obtained by cutting steel wires of various sizes may be used as long as the above grain size and components are satisfied.

If the groove angle is less than 30 °, the uniformity of the back bead deteriorates, and if the groove angle exceeds 55 °, the groove cross-sectional area becomes large and the welding efficiency is reduced.

By temporarily attaching the inner surface of the groove, gap fluctuation during welding can be reduced. When a ceramic solid backing material is used as the backing material BP, the backing material BP is supported against the material to be welded with a weak supporting force enough to join the backing material BP to the back surface of the welded portion. It is not necessary to use a magnet or a restraining jig. Therefore, labor can be reduced. The same effect can be obtained by using any of a copper plate backing material and a flux copper backing material combined with a glass tape in addition to the ceramic solid backing material as the backing material BP.

Incidentally, the temporary attachment to the inner surface of the groove may be a whole welding length or a partial welding length. Further, the height of the tacking bead is preferably 7 mm or less for stably bringing out the back bead, and 2 mm or more for perfect tacking. Also,
It is preferable that the root gap is 5 mm or less and the root face at the Y groove (see FIG. 3) is 3 mm or less, because the easiness of the plate joint welding and the back bead are stable. When the root gap exceeds 5 mm, the groove cross-sectional area becomes large, so that the welding efficiency decreases.

If the welding current density per wire cross-sectional area of the preceding welding electrode wire 9f is less than 230 A / mm ² , a stable back bead cannot be obtained. In particular, an unmelted portion occurs at the tacking portion. If the welding current density per wire cross-sectional area of the succeeding welding electrode wire 9b is less than 150 A / mm ² , poor penetration occurs. Although the preceding welding electrode wire 9f can provide good results in any of solid wires for mild steel and high-strength steel and low-temperature steel specified in JIS Z 3312 and Z 3325, it is particularly high in welding metal. When toughness is required, it is preferable to use a solid wire for low-temperature steel specified in JIS Z 3325.

Since the welding current density per wire cross-sectional area is high, the wire diameter is 1.4 m for the leading electrode wire 9f in order to improve welding workability and the shape of the back bead.
m or more and 2.0 mm or less, and 1.2 mm or more and 2.0 mm for the subsequent electrode wire 9b.
mm or less. The number of swings (times / minute) of the leading electrode wire 9f (torch Tf) is set to 40 times / minute or more and 150 times / minute or less in order to improve the shape of the back bead. 40
If it is less than times / minute, the bead waveform becomes coarse and a good back bead shape cannot be obtained. If it exceeds 150 times / minute, the arc becomes unstable and a good back bead shape cannot be obtained. The number of swings (times / minute) of the trailing electrode wire 9b is set to 30 times / minute or more and 120 times / minute or less in order to improve the shape of the front bead. If it is less than 30 times / minute, the bead waveform becomes coarse and a good surface bead shape cannot be obtained. At more than 120 times / minute, the arc becomes unstable and a good surface bead shape cannot be obtained. The swing width (oscillate width) of the electrode wire is changed stepwise according to the plate thickness in order to improve the bead surface. When the plate thickness is about 10 mm, the swing width of the leading electrode wire 9f is preferably 4 mm, and the swing width of the trailing electrode wire 9b is preferably 6 mm. When the board thickness is about 25 mm, the swing width of the leading electrode wire 9f is 10 mm, and Row electrode wire 9b
Is preferably 15 mm.

The inter-electrode distance Dw between the preceding and following electrode wires
In FIG. 6, if the diameter is less than 100 mm, the arc becomes unstable, and the back bead becomes too large. If the diameter exceeds 600 mm, the toughness is improved, but the size of the apparatus is undesirably large.

The welding speed is determined according to the plate thickness. For a plate thickness of about 10 mm, good welding at 40 cm / min to 45 cm / min and for a plate thickness of about 25 mm is 15 cm / min to 20 cm / min. It becomes possible.

Next, the relationship between the composition of the flux-cored wire used for the succeeding electrode wire 9b and the welding quality will be described.

TiO ₂ : 2.5% or more and 7.0% or less TiO ₂ exhibits properties as a slag forming agent and an arc stabilizer with respect to a weld bead. I can't. On the other hand, if the content exceeds 7.0%, the amount of oxygen in the weld metal increases, and large nonmetallic inclusions increase, so that the microstructure is not refined and the toughness is reduced. did.

ZrO ₂ : 0.4 or more and 1.0% or less ZrO ₂ enhances the solidification rate of the slag and the slag encapsulation of the molten metal to improve the bead appearance. Further, the vapor pressure at a high temperature is low, which is effective in making the droplets finer, and the sputtering is reduced. However, if the content is less than 0.4%, this effect cannot be obtained, and the appearance of the front bead becomes poor and the amount of spatter generated increases. On the other hand, if it exceeds 1.0%, the solidification temperature is high and defects such as slag entrapment are likely to occur. Therefore, the range is set to 0.4 or more and 1.0% or less.

Al ₂ O ₃ : 0.1% or more and 1.0% or less Al ₂ O ₃ , like ZrO ₂ , enhances the solidification rate of slag and the slag encapsulation of the molten metal to improve the bead appearance. However, if less than 0.1%, this effect cannot be obtained. 1.0%
If the ratio exceeds the range, defects such as slag entrainment occur and the slag removability deteriorates. Therefore, the range is set to 0.1% or more and 1.0% or less.

Si: 0.2 or more and 1.2% or less Si acts as a deoxidizing agent and is effective in reducing the oxygen content of the weld metal. However, if it is less than 0.2%, the deoxidizing power is insufficient and blowholes are generated, and if it exceeds 1.2%, the ferrite is solid-solution-hardened and the toughness is reduced. Therefore, the range is made 0.2 to 1.2%.

Mn: 1.0 or more and 4.0% or less Mn is effective in assisting deoxidation, increasing the fluidity of the molten metal, improving the bead shape, and improving the strength toughness. However, if it is less than 1.0%, deoxidation becomes insufficient and welding defects easily occur, and if it exceeds 4.0%, the weld metal becomes excessively deoxidized and pits and blowholes are easily generated, so the range is set to 1.0 or more and 4.0% or less. .

Mg: 0.1 or more and 1.0% or less Mg reacts with oxygen in a high-temperature arc, and a deoxidation reaction is performed at the stage of the droplet at the tip of the wire. As a result, the deoxidation product does not remain in the molten pool, further assists the deoxidation reaction of Si and Mn reacting in the molten pool, and is effective in reducing the amount of oxygen in the weld metal and improving the toughness. However, if it is less than 0.1%, the above effect is insufficient, and if it exceeds 1.0%, the arc length becomes excessively large and the bead shape deteriorates.
The range was 0.1% or more and 1.0% or less.

Na, K: One or two kinds of Na and K in total 0.003% or more and 0.3% or less Na and K have an effect of increasing arc stability and alleviating digging of a base material. However, if it is less than 0.03%, the above effects cannot be obtained. If it exceeds 0.3%, the arc length becomes too long, and the amount of spatter and fume increases.

When toughness at a low temperature is required, Ni, Ti and B are further added to the flux-cored wire in the following range.

Ni: 0.3 or more and 3.0% or less Ni is added in order to secure strength and low-temperature toughness.
If it is less than 0.3%, a sufficient toughness improving effect cannot be obtained.
%, 0.3% or more because hot cracking is likely to occur.3.
0%.

Ti: 0.02 or more and 0.2% or less Ti is a strong deoxidizing agent, prevents oxidation of weld metal,
The formation of the i-oxide refines the microstructure of the weld metal, which is effective in improving toughness. However, if the content is less than 0.02%, the effect of improving the toughness due to the refinement of the microstructure cannot be obtained.
If it exceeds 0.2%, carbides are remarkably formed and the toughness is impaired, so the range was made 0.02 or more and 0.2% or less.

B: 0.002 or more and 0.015% or less B is effective in refining the microstructure of the weld metal and improving the toughness. However, if the content is less than 0.002%, the effect of improving the toughness due to the refinement of the microstructure cannot be obtained, and if the content exceeds 0.015%, the crack resistance deteriorates, and carbides are formed to significantly impair the toughness. % Or less.

In order to further refine the microstructure of the weld metal and improve the toughness, Al: 0.30% or less, Zr:
It can be added in the range of 0.20% or less. Further, as adjustment of the strength of the weld metal, Cr can be added at 2.5% or less and Mo can be added at 2% or less.

In order to spray steel grains or iron powder in the groove,
As the leading electrode wire 9f, a steel wire having a deeper penetration than a flux-cored wire is used, but the current density per wire cross-sectional area is increased, and the amount of spatter generated is large because the electrode wire swings. Therefore, at least the leading electrode wire 9f is double-shielded in order to have a high shielding effect and reduce the amount of spatter generated. According to the welding conditions shown in Table 2, the amount of spatter generated in the preceding welding, in which the amount of spatter was particularly large, was investigated.

[0059]

[Table 2]

The current was changed in three stages of 300 A, 400 A, and 500 A, and the amount of spatter generated when the conventional method (single shield) and the double shield were used was investigated. Usually, the amount of spatter generated by the conventional method increases as the current increases,
Since it was about 5.0 g / min, less than that was evaluated as good. FIG. 7 shows the relationship between the welding current and the amount of spatter generated. With double shielding, the amount of spatter generated was 2.0 g / min or less irrespective of the change in current as compared with the conventional method (single shield).

The results of the experiment are shown below.

-Experiment 1- A steel material shown in Table 3 was combined with a steel wire for the leading electrode (9f) shown in Table 4 and a flux-cored wire for the succeeding electrode (9b) shown in Table 5; Weld length 1500mm with groove shape, steel grain or iron powder spraying and welding conditions shown in 11
Was performed by single-sided gas shielded arc welding. The welding speed was from 15 m / min to 450 m / min depending on the plate thickness. In addition, the temporary attachment of the groove | channel inner surface was performed in 30 places of 30 mm length every 300 mm using the coating arc welding rod. After welding,
The front and back bead appearance, the presence or absence of cracks, and the impact value were investigated. The impact value was measured in JIS Z from the center of the thickness of the specimen after welding.
2202 No. 4 impact test piece was sampled and its impact value was measured at 0 ° C. The presence or absence of cracks was examined by a penetration test and a macro section. The results are also summarized in Tables 6 to 11. Tables 6 to 11 are obtained by dividing one large table into six, and these tables are arranged as the following arrays. Table 6 Table 8 Table 10 Table 7 Table 9 Table 11 Overlapping notations in adjacent tables Are superimposed and arranged on the same plane, one table appears.

[0063]

[Table 3]

[0064]

[Table 4]

[0065]

[Table 5]

[0066]

[Table 6]

[0067]

[Table 7]

[0068]

[Table 8]

[0069]

[Table 9]

[0070]

[Table 10]

[0071]

[Table 11]

In Tables 6 to 11, No. Nos. 1 to 8 are preferred experimental examples; 9 to 28 are comparative examples. In the preferred experimental example, No. Nos. 1 to 8 are suitable for the groove shape, the sprinkling height of steel grains or iron powder, the number of times of electrode swing, the welding current density, and the wire component of the succeeding electrode 9b. Because it was a heavy shield,
Both the front and back bead appearances were good, there were no defects such as hot cracks, and the impact value was extremely good.

In the comparative examples, No. In No. 9, since the amount of sprayed steel particles was low, burn-through of the weld metal occurred. No. 10 is
The back bead did not appear due to the high spraying rate of the steel grains. N
o. No. 11 had a wide groove, little swelling due to welding, and too much back bead. Further, since the Si of the subsequent electrode wire 9b (F6) was high, the toughness was low, and the Mg content was high, so that the appearance of the front bead was poor. No. 12
Is that the back bead is not uniform because the groove angle is narrow, and the Si and Mn of the subsequent electrode wire 9b (F5) are low.
Blowhole occurred. No. In No. 13, blow holes occurred because Mn of the subsequent electrode wire 9b (F7) was high. Further, since the total amount of Na and K was large, the amount of spatter generated was large. No. 14 is a trailing electrode wire 9b
(F8) has a low Mg content, and thus has low toughness.
Since the total amount of K was small, the arc became unstable and the surface bead became defective. No. 15 is the leading electrode wire 9
Since the welding current density of f was low, no back bead appeared.
No. In No. 16, since the welding current density of the trailing electrode wire 9b was low, the appearance of the front bead was poor. No. 17
Since the number of swings of the leading electrode wire 9f was small, the back beads became uneven. No. In No. 18, since the number of swings of the trailing electrode wire 9b was small, the external bead appearance was poor. No. In No. 19, since the number of swings of the leading electrode wire 9f was large, the arc became unstable and the back beads became uneven. No. In No. 20, since the number of swings of the trailing electrode wire 9b was large, the arc was unstable and the front bead was defective. No. 21 is a leading and trailing electrode wire 9f, 9
Since the inter-electrode distance Dw of b was small, the arc became unstable, and burn-through of the weld metal occurred. No. 22
Since the amount of TiO ₂ in the subsequent electrode wire 9b (F9) was small, the appearance of the front bead was poor. No. 23 has a large amount of TiO ₂ in the subsequent electrode wire 9b (F10),
The toughness was low. No. 24 is a trailing electrode wire 9b
Since the amount of ZrO _{2 in} (F11) was small, the slag encapsulation property in the molten metal was poor, the bead appearance was poor, and the amount of spatter generated was large. No. 25 is a trailing electrode wire 9b (F
12) ZrO ₂ is large, so slag entrainment occurred. No. 26 is A of the following electrode wire 9b (F13).
Since the amount of l ₂ O ₃ was small, the slag encapsulation in the weld metal was poor and the appearance of the front bead was poor. No. In No. 27, since the amount of Al ₂ O ₃ in the subsequent electrode wire 9b (F14) was large, a slag entrainment defect occurred, and slag peeling became poor. N
o. In No. 28, the amount of spatter was increased because no double shielding was performed.

-Experiment 2- Example 1 was performed by combining a steel material for low temperature shown in Table 12 with a steel wire shown in Table 4 and a flux-cored wire shown in Table 13.
In the same manner as in the above, two-electrode single-sided gas shielded arc welding was performed.
In each test, the leading and trailing electrode wires 9f, 9b
Was double shielded. For evaluation of toughness, the impact value at −20 ° C. was examined. The results are shown in Tables 14, 15, and 1.
6 are shown together. In addition, Table 14 to Table 16 are obtained by dividing one large table into three, and these tables are arranged as the following arrays. Table 14 Table 15 Table 16 Overlapping notation parts in adjacent tables are superimposed on the same plane. By arranging above, one table appears.

[0075]

[Table 12]

[0076]

[Table 13]

[0077]

[Table 14]

[0078]

[Table 15]

[0079]

[Table 16]

No. in Tables 14 to 16 No. 29 to 33 are experimental examples of the preferred welding method. 34 to 39 are comparative examples. In the preferred experimental example, No. 29-33
Are the groove shape, the sprinkling height of steel grains or iron powder, the number of electrode swings, the welding current density, and the following electrode wire 9b (F15
To F18: The filling flux components shown in Table 13) are appropriate, and the leading and trailing welding electrode wires 9f and 9b are double shielded, so that both the front and back bead appearances are good.
There was no defect such as hot cracking and the toughness was very good.

In the comparative examples, No. 34 is a trailing electrode wire 9
Since the Ni of b (F19) was small, the toughness was low. N
o. In No. 35, high temperature cracking occurred because the trailing electrode wire 9b (F20) contained a large amount of Ni. No. In No. 36, the toughness was low because the amount of Ti in the subsequent electrode wire 9b (F21) was small. No. No. 37 has low toughness because the trailing electrode wire 9b (F22) has a large amount of Ti. No. No. 38 had low toughness because B of the subsequent electrode wire 9b (F23) was small. No. 39 is a trailing electrode wire 9b (F24)
Since there was a lot of B inside, hot cracking occurred.

According to the experimental examples of the preferred welding methods of Experimental Examples 1 and 2 described in detail above, one-sided welding of a short to long welded structure is performed by welding workability, cracking resistance and back, front bead. Good weldability, a sound and high toughness welded area can be obtained, and the groove cross-section can be reduced. One-run welding, which does not require complicated operations during welding, greatly improves the work efficiency. it can.

[Brief description of the drawings]

FIG. 1 is a side view of an apparatus A according to an embodiment of the present invention, in which a groove and a backing material BP show a longitudinal section.

2A-2A of FIG. 1 of the welding apparatus A shown in FIG. 1;
It is a line sectional view.

FIG. 3 is a block diagram showing a system configuration for oscillating a preceding welding torch Tf and a succeeding welding torch Tb shown in FIG. 1, and welding target materials WR and WL are shown in perspective views.

FIG. 4 is an enlarged vertical sectional view of a double shield 100b mounted on the welding torch Tb shown in FIG.

FIG. 5 is a graph showing a distribution of a combination of a sheet thickness and a steel grain scattering height when welding a groove of a material having several sheet thicknesses under welding conditions shown in Table 1 in the specification. Yes, a symbol indicating the quality of the back bead shape was given to each combination point.

6 is a front electrode wire 9 of the welding apparatus A shown in FIG.
It is a side view which shows the distance between f and the succeeding electrode wire 9b, ie, the distance Dw between poles.

FIG. 7 is a graph showing a relationship between a welding current value and a spatter generation amount, and the conventional method on the graph shows a case of a single shield.

[Explanation of symbols]

A: Welding device r: Rail Sf: Leading sensor Sb: Trailing sensor Tf: Trailing welding torch Tb: Trailing welding torch WL, WR: Work Wo: Central position of groove 1: Bogie 2fL, 2fR, 2bL, 2bR: Wheel 3f, 3b: grooved rollers 11, 12: bogie frame 13: support plate 21: shaft 23, 24: sprocket wheel M1: bogie drive motor 4f, 4b: sensor support mechanism 41, 42: arm 43: support Arms 44, 45: Screws 5f, 5b: Sensor oscillating mechanism 51: Frame 52: Screw rod 53: Guide rail 54: Slider 55f: Supporting rod M5f: Leading sensor oscillating motor 6f, 6b: Torch oscillating mechanism 80f, 80b: Torch support Mechanism 81: Support arm 81a: Screw 82: Support board 83: Rotating board 84: Set screw 85: Screw 86: Pin 87 Torch holding member M8f: Torch rotation motor 7: Frame 9f: Hand-operated end 100f, 100b: Double shield 101: Attachment 102: Inner nozzle 103: Outer nozzle MDf1, MDF2, MDF3: Stepping motor driver PF: Welding power supply 110 : Contact detection circuit 200: Control circuit

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI B23K 35/368 B23K 35/368 B (72) Inventor Tadashi Hoshino 7-6-1 Higashi Narashino, Narashino-shi, Chiba Nippon Steel Welding Industry (72) Inventor Hirofumi Sano 3-5-4 Tsukiji, Chuo-ku, Tokyo Nippon Steel Welding Industry Co., Ltd. Research Laboratory (56) Reference JP-A-62-61798 (JP, A) JP-A-9-206945 (JP, A) JP-A-63-235077 (JP, A) JP-B-7-63843 (JP, B2) JP-B-53-19298 (JP, B2) JP-B-61-9114 (JP, A) JP, B2) JP 4-33548 (JP, B2) JP 50-24254 (JP, B1) JP 2-24545 (JP, Y2) (58) Fields surveyed (Int. Cl. ⁷ , (DB name) B23K 9/095 B23K 9/00 B23K 9/035 B23K 9/16 B23K 33/00 B23K 35 / 368

Claims (4)

(57) [Claims] 1. A backing material to be applied to the back surface of a Y or V-shaped groove having a groove angle of 30 to 55 °, a steel grain or iron powder to be filled in the groove, and the groove. A two-sided gas shielded arc welding torch arranged in the direction in which the groove extends and mounted on the carriage and facing the groove; and the two welding torches are swung. drive to DOO - Chi swinging mechanism, and the two welding bets - at least the one switch, for adjusting the inclination with respect to the direction in which the groove extends bets - Chi angle adjusting mechanism comprises, of the carriage Preceding welding toe on the upstream side in the running direction
H welding electrode wire is a solid wire, after it becomes downstream
The welding electrode wire of the row welding torch is a flux-cored wire
Der Ru, 2 electrodes one side gas-shielded arc welding apparatus. 2. The apparatus according to claim 1, further comprising a rotatable roller supported by said carriage and engaged with a rail installed on the work to be welded substantially in parallel with said groove. Electrode single-sided gas shielded arc welding equipment. 3. The two-electrode single-sided gas shielded arc welding apparatus according to claim 1, wherein the distance between the welding electrode wires of the two welding torches is 100 mm or more and 600 mm or less. 4. A welding electrode wire of a succeeding welding torch, which is a downstream side in the traveling direction of the bogie, of the two welding torches, is TiO. _2: 2.5% to 7.0% or less ZrO _2: 0.4% to 1.0% or less Al ₂ O _2: 0.1% to 1.0% or less Si: 0.2% to 1.2% or less Mn: 1.0% to 4.0% or less Mg: 0.1% or more 1.0 % Or less, and the sum of one or two of Na and K
The two-electrode single-sided gas shielded arc welding apparatus according to claim 1, wherein the wire is a flux-cored wire filled with a flux of 0.03% or more and 0.3% or less.