JPH0985447A - Submerged arc welding method of box column angle joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a submerged arc welding method of a box column angle joint not requiring edge preparation and capable of improving welding efficiency in producing a box column. SOLUTION: In a submerged arc welding to weld a box column angle joint with multi-electrodes of two or more, by perpendicularly butting a plate 1 to be welded of a thickness t (mm) not having edge preparation with a plate 2 to be welded and spacing between both plates by a prescribed distance (gap G), I shaped groove is arranged. A backing 3 is placed at the corner part of the inside of angle joint formed in this way, a wire having diameter D (mm) is inserted into the groove from the upper side of plate 1 to be welded and a single layer welding is executed by submerged arc welding, a weld metal 4 is formed. At this time, welding is executed so that D>=4.8mm, 25mm<=t<=50 mm and D+1mm<=G<=3×Dmm are satisfied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a submerged arc welding execution method, and more particularly to a submerged arc welding execution method for box column corner joints in which the groove of the weld is welded as an I-shape.

[0002]

2. Description of the Related Art FIGS. 6, 7 and 8 are sectional views showing a corner joint portion of a box column welded by a conventional welding construction method.

In the welding method shown in FIG. 6, the plate 2 to be welded is used.
35 ° groove processing is applied to the end of 1 by gas cutting,
7 m between the end of the welded plate 21 and the surface of the welded plate 22
A gap G of m is provided, and these welded plates 21 and 2 are
The plates to be welded 21 and 22 are assembled and fixed by a fixing means such as a welding fixture so that the two are perpendicular to each other. Then, the backing material 23 is arranged at the inner corner of the corner joint, and the weld metal 25 is formed from the upper part of the plate 21 to be welded to the bottom of the groove by carbon dioxide gas arc welding. After that, the single-layer weld metal 24 is formed on the upper portion of the multi-layer weld metal 25 by submerged arc welding. It is also possible to form the corner joint of the box column by joining the plates to be welded 21 and 22 by stacking all the grooves in multiple layers by carbon dioxide arc welding.

In the case of the groove shape shown in FIG. 6, when the carbon dioxide gas arc welding and the submerged arc welding described above are used for welding, or when the carbon dioxide gas arc welding alone is used for welding, the thickness of the plate 21 to be welded is There is no particular limitation.

The welding method shown in FIG. 7 is a typical welding method when the plate 31 to be welded is a thin plate having a thickness of 32 mm or less. In this welding construction method, a 40-degree square groove process is performed on the end portion of the plate 31 to be welded, and 2
mm root face is formed, and the root face of the plate 31 to be welded is abutted against the surface of the plate 32 to be welded, and arranged so as to be perpendicular to each other. Then, the backing material 33 is arranged at the inner corner of the corner joint, the wire is inserted into the groove from above the plate 31 to be welded, and submerged arc welding is performed to form the single-layer weld metal 34. There is.

The welding method shown in FIG. 8 is a typical welding method when the plate 41 to be welded is a medium-thickness plate having a thickness of 36 to 50 mm. In this welding construction method, the Y-shaped groove whose angle is 35 ° is applied to the ends of the plates to be welded 41 and 42, and a root face of 2 mm is formed on the plate to be welded 41. The root face of is welded to the surface of the plate to be welded 42, and the plates to be welded 41 and 42 are arranged so as to be perpendicular to each other. Then, the backing material 43 is arranged at the inner corner of the corner joint, the wire is inserted into the groove from above the plate 41 to be welded, and submerged arc welding using two electrodes or three electrodes is performed. A layer of weld metal 44 is formed.

[0007]

However, in the above-described box column corner joint welding, before the welding is started,
In both cases, it is necessary to perform groove processing on the end portion of the plate to be welded by gas cutting or the like, so that the efficiency of the welding process in manufacturing the box column is extremely poor.

The present invention has been made in view of the above problems, and it is a submerged arc welding process for box column corner joints that can improve the efficiency of the welding process in the production of box columns without the need for groove processing. The purpose is to provide a method.

[0009]

A submerged arc welding method for a box column corner joint according to the present invention has a thickness t (m).
Submerged arc welding for welding the corner joint part of a box column, which is formed by abutting the end surface of the plate to be welded to another plate to be welded with each other with an I-shaped groove between them, with two or more electrodes. In the method, if the diameter of the wire is D (mm) and the groove gap is G (mm), D ≧
4.8 (mm), and the thinnest wire is D + 1 (m
m) ≦ G ≦ 3 × D (mm), and the thickness t is 25
(Mm) ≦ t ≦ 50 (mm), and the I-shaped groove of the corner joint portion is welded by a single layer.

[0010]

In the present invention, the plates to be welded having the thickness t (mm) are arranged so that their end faces are abutted against the surface of another plate to be welded and are perpendicular to each other. In this case, the end face is not grooved. Therefore, in the present invention, the groove of the corner joint portion of the box column is an I-shaped groove, a gap G is provided in this I-shaped groove, and a wire of a predetermined diameter is used to perform single-piece welding by submerged arc welding. Weld layers. In the present invention,
Since the wire diameter, plate thickness and groove gap are set appropriately, it is possible to perform submerged arc welding with a gap I-shaped groove and it is not necessary to provide a groove that requires a long time for processing. The process efficiency can be improved.

In the method of submerged arc welding for box column corner joints according to the present invention, welding is performed with two or more electrodes. This is because welding with a single electrode not only slows down the welding speed, but also causes hot cracking and prevents the bead cross-sectional shape from becoming pear-shaped.

Next, the relationship between the diameter of the wire used in the submerged arc welding method according to the present invention, the thickness of the plate to be welded, the welding gap and the diameter of the wire will be described.

Wire diameter D: D ≧ 4.8 mm In submerged arc welding, since a high current of 1000 A or more is passed through the wire, the bead width cannot be sufficiently widened in the case of a small diameter wire, and defects such as defective fusion are caused. Is likely to occur. Further, if the diameter of the wire is small, the welding of the plate to be welded tends to be unstable, and defects such as defective welding or slag entrainment will occur. In order to weld without causing such defects, the wire diameter D needs to satisfy D ≧ 4.8 mm.

Thickness t of the plate to be welded: 25 mm≤t≤50 m
m When the thickness t of the plate to be welded is t <25 mm, the groove cross-sectional area becomes large as compared with the conventional case where a groove is formed at a predetermined angle on the end of the plate to be welded. The difference becomes more remarkable as the thickness t of the plate to be welded becomes smaller.

For example, when the thickness of the plate to be welded is 50 mm, the root surface of the conventional 35 ° groove is 2 mm.
Then, the groove cross-sectional area is (48 × 33.6 ÷ 2 =) 80
6 mm ^2. On the other hand in the submerged arc welding method according to the present invention, the gap G of the welding plates 5.8mm
Then, the groove cross-sectional area is (50 x 5.8 =) 290 mm
It becomes as small as ² . However, if the thickness of the plate to be welded is 10 mm, the root surface of the conventional 35 ° groove is 2 mm.
Then, the groove cross-sectional area is (8 × 5.6 ÷ 2 =) 22.4
mm ² , while in the submerged arc welding method according to the present invention, the gap G is 50 mm
Similarly to the above-mentioned case, when the groove width is set to 5.8 mm, the groove cross-sectional area becomes as large as (10 × 5.8 =) 58 mm ² .

As described above, the thickness t of the plate to be welded is 25 mm.
If it becomes smaller, the groove cross-sectional area becomes larger, so the efficiency of the welding process cannot be improved,
In addition, it is not preferable from the economical point of view.

On the other hand, when the thickness t of the plate to be welded is t> 50 mm, it is difficult to secure the penetration over the entire groove surface, and as a result, defective fusion occurs on the groove surface. I will end up. Therefore, the thickness t of the plate to be welded is 25 mm.
It is necessary to satisfy ≦ t ≦ 50 mm.

The relationship between the welding gap G and the wire diameter D
Relation: D + 1 mm ≦ G ≦ 3 × Dmm Between the welding gap between the plates to be welded and the diameter of the wire,
It is necessary to satisfy the above relationship. G <D + 1mm
If so, the gap becomes too narrow, and even if the welding conditions are adjusted, defects such as insufficient penetration of the welded portion in the plate to be welded or slag entrainment at the groove bottom are likely to occur.

On the other hand, if G> 3 × Dmm, the cross-sectional area of the groove becomes too wide, which lowers the efficiency of the welding process and is also not preferable from the economical point of view. In addition, defects such as poor fusion of both groove surfaces of the plate to be welded are likely to occur.

[0020]

Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. FIG. 1 is a sectional view showing a corner joint portion of a box column welded by a submerged arc welding method according to an embodiment of the present invention.

As shown in FIG. 1, welded plates 1 and 2
No groove processing such as V-shape and Y-shape as in the prior art is applied to the end of the, but the end face of the plate 1 to be welded is abutted from the surface of the plate 2 to be welded by a predetermined distance (gap G). I-shaped groove. The plates 1 and 2 to be welded are assembled and fixed by a fixing means such as a welding fixture so that the plates 1 and 2 to be welded are maintained in a state of being perpendicular to each other. Then, the backing material 3 was arranged at the inner corner of the corner joint, a wire having a predetermined diameter was inserted into the groove from above the plate 1 to be welded, and submerged arc welding was performed to form the weld metal 4.

Table 1 below shows the plate thickness t of the plates 1 and 2 to be welded used in this example, and the component composition at each plate thickness. The steel type of the plate to be welded used is SM-490A.

[0023]

[Table 1] Table 2 below shows the diameters of the wires used and the component compositions of the respective wires.

[0024]

[Table 2]

Submerged arc welding was performed using the electrodes to be welded and the wires shown in Tables 1 and 2 above and two electrodes. FIG. 2 is a schematic diagram showing the arrangement of the wire electrodes at that time. As shown in FIG. 2, the leading electrode wire electrode 11 and the trailing electrode wire electrode 12 are inclined 3 degrees and 5 degrees with respect to the vertical direction, respectively, and the contact tip 13
And 14 to the surface of the plate 1 to be welded
_L and H _T are 40 and 50 mm, respectively, and the electrode distance K is 60
The corner joint portions of the plates 1 and 2 to be welded were welded in mm.
The wire used is JIS Z3351 YS-S.
6 and the flux is JIS Z3352 FS
-BT1.

Using the plate and wire to be welded as described above, the corner joint portion of the box column was welded under the welding conditions shown in Table 3 below. Welding results obtained by investigating the condition of the welded portion by X-ray are also shown in Table 3 below. In the column of wire diameter, the leading wire electrode 11 is L and the trailing wire electrode 12 is T, and the respective diameters are shown. Further, for the conditions outside the scope of the claims of the present invention, the values are underlined.

[0027]

[Table 3]

As shown in Table 3 above, Examples No. 1 to No. 4
Regarding No. 3, there was no defect, and a good weld was able to be obtained.

On the other hand, in Comparative Example No. 1, since the wire used was thin, as shown in FIG. 3, slag entrainment 5 occurred at the bottom of the groove, and fusion failure occurred at the groove side. Further, since the plates 1 and 2 to be welded are thin, the welding speed is reduced to 2/3 as compared with the conventional welding method, and the welding efficiency is reduced.

In Comparative Example No. 2, since the plates 1 and 2 to be welded were thick and the gap was small, insufficient penetration occurred at the bottom of the groove, and as shown in FIG. Crack 6 occurred.

Since Comparative Example No. 3 was welded with a single electrode, hot cracking due to the pear shape was generated as in Comparative Example No. 2 and the bead appearance was inferior to that of the Example. In addition, the welding speed is 1/100 compared to the conventional welding method.
The welding efficiency was lowered to 2.

In Comparative Example No. 4, since the wire used was thin and the size of the gap was large, as shown in FIG. 5, slag entrainment 7 occurred in the groove side portion, and fusion failure occurred.

[0033]

As described above, according to the present invention,
The groove of the corner joint of the box column is an I-shaped groove, and a wire having a predetermined diameter is used for this welding, and submerged arc welding is performed so that the gap between the plates to be welded and the wire have a predetermined relationship. Therefore, it is not necessary to provide a groove having a shape which requires a long time for its processing. Therefore, the efficiency of the welding process in manufacturing the box column can be improved, and the box column in which the corner joint portion is well welded can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a corner joint portion of a box column welded by a submerged arc welding method according to an embodiment of the present invention.

FIG. 2 is a schematic view showing the arrangement of wire electrodes used in the submerged arc welding method according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a welding defect of a welded portion (poor fusion of a groove bottom portion).

FIG. 4 is a cross-sectional view showing a welding defect (pear-shaped hot cracking) of a welded portion.

FIG. 5 is a cross-sectional view showing a welding defect in a welded portion (poor fusion on the groove side portion).

FIG. 6 is a sectional view showing a corner joint portion of a box column welded by a conventional welding construction method.

FIG. 7 is a cross-sectional view showing a corner joint portion of a box column welded by a conventional submerged arc welding method.

FIG. 8 is a sectional view showing a corner joint portion of a box column welded by a conventional submerged arc welding method.

[Explanation of symbols]

1, 2, 21, 22, 31, 32, 41, 42; Welded plate 3, 23, 33, 43; Backing material 4, 24, 34, 44; Weld metal 5, 7; Slag inclusion 6; Crack 11, 12; Wire electrode 13, 14; Contact tip 25; Multi-layer weld metal

Claims (1)

[Claims] 1. A box column corner joint part formed by abutting an end surface of a plate to be welded having a thickness t (mm) with another plate to be welded by providing an I-shaped groove between them and having two or more electrodes. In the submerged arc welding method for welding with the multi-electrode, when the diameter of the wire is D (mm) and the groove gap is G (mm), all wires have D ≧ 4.8 (mm),
The thinnest wire is D + 1 (mm) ≤ G ≤ 3 x D (mm)
And the thickness t is 25 (mm) ≦ t ≦ 50 (m
m) and a single layer welding of the I-shaped groove of the corner joint portion, a submerged arc welding method for box column corner joints.