JP5949539B2 - Electrogas arc welding method - Google Patents

Description

  The present invention relates to an electrogas arc welding method, and in particular, an electroplated butt-welded joint in which a steel sheet as a material to be welded is bent and arranged in a chevron shape with a welding line as an axis toward a groove back surface side. The present invention relates to a gas arc welding method.

The electrogas arc welding method is a high-efficiency automatic welding method as disclosed in Patent Document 1, and is widely used for welding construction of large structures such as shipbuilding, energy industry and construction.
As shown in FIGS. 5 (a) and 5 (b), the electrogas arc welding method uses a groove 2 formed by two adjacent steel plates 1 and 1 standing vertically. A fixed backing material (hereinafter abbreviated as backing material) 3 is disposed on the back surface, and water-cooled sliding copper metal 4 is applied to the front surface to provide the backing material 3, sliding copper metal 4 and steel plate 1. 1, the tip of the welding torch 5 is inserted into the space surrounded by 1, and the welding wire 7, which is a consumable electrode, is continuously supplied from the welding torch 5 to the space to generate between the molten pool 8 and the welding wire 7 This is a welding method in which the welding wire 7 is melted by the heat of the arc to form a weld metal 9 and welded.

  During welding, a shield gas is supplied from a shield gas supply pipe 12 into a shield gas hood 6 provided on the upper part of the water-cooled sliding copper metal 4 to cut off the space from the atmosphere so that there is no blowhole. To form a weld metal. Cooling water is supplied from the cooling water supply pipe 11 into the sliding copper metal 4.

In welding, the water-cooled sliding copper metal 4 and the welding torch 5 are mounted on a welding carriage (not shown), and the welding torch 5 and the water-cooled sliding copper are aligned with the upper surface of the molten pool 8 that rises as welding progresses. The money 4 is raised sequentially. A molten slag 10 is generated on the molten pool 8 along with the welding. The molten slag 10 is appropriately discharged from between the surface of the weld bead and the bead forming groove 13 of the water-cooled sliding copper metal 4 and solidifies while covering the surface of the weld bead to improve the appearance of the weld bead. Moreover, the backing material 3 forms a good back bead while preventing the molten metal from leaking from the back side.
In addition, although the example which interposed the glass tape 15 between the steel plate 1 and the backing material 3 was shown in FIG. 5, a backing material can also be directly attached to a steel plate without interposing the glass tape 15. FIG.

In a normal butt-welded joint as shown in FIG. 5, since a flat steel plate is arranged on the same plane and welding is performed, the shape of a surface 16 (hereinafter referred to as a facing surface) 16 facing the steel plate of the backing material 3. Was a shape corresponding to the plane.
In recent years, there is a demand for manufacturing a large cylindrical body by preparing a long plate material having a shape obtained by dividing a large cylindrical body in a vertical direction as disclosed in Patent Document 2, and sequentially welding them together. In such welding, the steel plates 1 and 1 are welded by placing them in a state of being bent into a mountain shape with the groove back surface side inside with the welding line as an axis, as shown in FIG. In some cases, a vertical butt weld joint is formed that is bent at an inner angle θw of 140 to 170 °.

Japanese Patent Laid-Open No. 11-285826 JP 2011-115829 A

In order to form an upright butt welded joint bent into a chevron shape as shown in FIG. 1 by electrogas arc welding, the opposing surface 16 is usually inclined on the steel plate side as shown in FIG. The backing material 3 in which the recessed portion 17 for back bead surplus is formed is used, and welding is performed by arranging the backing material in FIG. 3 (a) so as to contact the steel plate surface.
Normally, the inner angle (opposite surface inner angle) θb between the facing surfaces 16 and 16 of the backing material is equal to the bending angle θw of the joint so that there is a gap between the backing material 3 and the steel plate 1. It is not formed.

However, in actual welding, it is quite difficult to temporarily assemble the steel sheet with the accuracy of the joint bending angle θw as designed, and the bending angle θw becomes smaller than the design value, so that When smaller than the angle θb (hereinafter abbreviated as the angle θb of the backing material), a gap is formed between the surface of the steel plate 1 and the opposing surface 16 of the backing material as shown in FIG. Overlap will occur in the rear back bead.
Therefore, in the electrogas arc welding of the vertical butt weld joint in which the steel plate as the material to be welded is bent in a mountain shape toward the groove back surface side with the welding line as an axis, even if the accuracy of the temporary assembly of the steel plate is somewhat poor It is an object of the present invention to enable welding without causing a welding defect in the back bead.

The inventors of the present invention have intensively studied a method for solving the above-described problems. As a result, instead of bringing the entire steel plate facing surface of the backing material into contact with the steel plate surface as in the prior art, if the corners of the recess for back bead surfacing are brought into contact with the steel plate surface, The present invention was made by finding that no gap was formed between the steel plate and the opposing surface of this material, and welding was possible without leakage of molten metal or formation of overlap.
The gist of the present invention is as follows.

(1) A vertical butt-welded joint in which a steel plate to be welded is bent and arranged in a chevron shape in a range of angle θw: 140 to 170 ° with the groove back surface inside the welding line as an axis, In an electrogas arc welding method in which a fixed backing material is disposed on the back side of the groove and a water-cooled sliding copper alloy is disposed on the front side and welding is performed using a consumable electrode, the surface of the fixed backing material that faces the steel plate An electrogas arc welding method characterized in that welding is carried out by placing a fixed backing material having an inner angle θb of (θw−28) to (θw−2) degrees.

(2) The electrogas arc welding method according to (1), wherein the fixed backing material is made of ceramics.
(3) The electrogas arc welding method according to (1), wherein the fixed backing material is made of copper.
(4) The electrogas arc welding method according to any one of (1) to (3), wherein a glass tape is disposed between a steel plate surface and the fixed backing material.
(5) The above-described (1) to (4), wherein the water-cooled sliding copper metal disposed on the front side of the groove is a metal having a surface abutting on the steel plate surface formed on the same plane. The electrogas arc welding method according to any one of the above.
(6) The electrogas arc welding method according to any one of (1) to (5), wherein the consumable electrode is a flux-cored wire.

  In an electrogas arc welding of a vertical butt weld joint in which a steel plate which is a material to be welded is bent in a mountain shape with the welding line as an axis toward the groove back surface side, the inner angle θb of the surface facing the steel plate is (θw−28) degrees. By arranging and fixing the fixed backing material formed at ~ (θw-2) degrees, welding can be performed without causing welding defects in the back bead even if the temporary assembly accuracy of the steel sheet is somewhat poor. .

It is a figure which shows the vertical butt-welded joint by which the steel plate which is a to-be-welded material was bent in the mountain shape toward the groove back surface side by using a welding line as an axis | shaft. It is a figure which shows the fixed backing material used when forming the vertical butt-welded joint bent in the mountain shape by electrogas arc welding. It is a figure which shows the aspect of a steel plate and backing material in case the relationship between the bending angle (theta) w of a steel plate and the opposing surface angle (theta) b of backing material differs, (a) is (theta) b = (theta) w, (b) is (theta) b> (theta) w, ( c) shows the case of θb ≦ θw, and (d) shows the case of θb <θw−28 degrees. It is a figure which shows the outline | summary of the electrogas arc welding of the vertical butt-welding joint bent in the mountain shape. It is a figure which shows the outline | summary of the electrogas arc welding of a general vertical butt-welding joint.

  In vertical electrogas arc welding, welding is performed using a backing material having a shape in which the molten metal matches the shape of the joint. When welding a vertical butt-welded joint that is bent in a chevron shape toward the back side of the groove as shown in FIG. 1, the angle θb of the backing material 3 as shown in FIG. The backing material 3 formed at an angle similar to the bending angle θw is used.

In that case, if the accuracy (temporary assembly accuracy) when two steel plates are temporarily assembled at a predetermined angle with a groove sandwiched for welding is ± 0 degrees, θb as shown in FIG. = Θw causes no particular problem. However, in practice, it is quite difficult to set the temporary assembly accuracy to ± 0 degrees. When the groove accuracy is poor and θb> θw, a gap as shown in FIG. 3C is generated between the mounting surface of the backing material and the steel plate surface, and the back bead overlaps.
Therefore, in consideration of the groove accuracy, it may not be possible to prevent the occurrence of welding defects when θb = θw, and when θb> θw, overlap is likely to occur, which is not appropriate.

  The present inventor does not bring the entire facing surface 16 into contact with the steel plate surface, but makes the back surface of the concave portion 17 (see FIG. 2) of the back bead surfacing contact with the steel plate surface. Considering that the gap between the steel plate and the opposing surface of this material is not formed, and that welding is possible without leakage of molten metal or overlap, the shape of the backing material is examined based on this idea. did.

In order to bring the corner 18 of the back bead extra-concave recess 17 into contact with the steel plate surface, as shown in FIG. 3B, the angle θb of the backing material <the angle θw between the steel plates. There is a need.
Therefore, first, backing materials having various facing surface inner angles θb are created in a range where the value of (θw−θb) is −2 to 32 degrees, and the created backing material is shown in FIG. It was set as shown, and the vertical electrogas arc welding of the steel plates arranged at the bending angle θw was performed, and the effectiveness of setting θb <θw was confirmed. At that time, as the sliding copper alloy on the front surface side, a flat one in which the surface in contact with the steel plate shown in FIG. 4 is arranged on the same plane was used.

  The results are shown in Table 1, and a result that a good back bead is formed over the range of (θw−θb) in the range of 0 ° to 30 ° is obtained, and as shown in FIG. The effectiveness of bringing the corners of the recesses into contact with the steel plate surface was confirmed. In addition, when θb> θw, as shown in FIG. 3C, an overlap occurs in the back bead, and when θb is excessively small with respect to θw as shown in FIG. 3D, the molten metal leaks. It was also confirmed that

From the above experiment,
Since good results were obtained in the range of 0 degrees ≦ (θw−θb) ≦ 30 degrees, even when the angle θwa between the actual steel plates is set to be deviated from the design value θw, always θb ≦ A study was made on θwa and θb ≧ θwa−30 degrees.
As a result, it was found that (θw−28) degrees ≦ θb ≦ (θw−2) degrees may be satisfied.

That is, as a result of the investigation of the temporary assembly accuracy of the actual steel sheet by the present inventors, it was confirmed that the bending angle of the temporarily assembled steel sheet was almost within the range of ± 2 degrees of the design value in the investigated range.
Accordingly, the angle θb of the backing material is set to a value that is 2 degrees smaller than the design value θw of the bending angle of the joint, that is, θb = (θw−2) degrees, so that the actual angle between the steel sheets θwa = design value Even in the case of θw−2 degrees, θb = θwa. Therefore, the upper limit of θb is set to (θw−2) degrees as a limit that does not cause overlap. From the viewpoint of preventing overlap, the upper limit is preferably (θw−3) degrees.
The lower limit of θb was set to (θw−28 degrees) in the same manner as in Table 1 as the limit at which the molten metal did not leak.

Next, the sliding copper contact on the groove surface side was also examined.
It is common for the sliding copper alloy to have a shape in which the surface 14 in contact with the steel plate is inclined according to the bending angle of the steel plate, but in that case, in relation to the temporary assembly accuracy of the steel plate. It is expected that problems similar to those of the backing material will occur.

  Therefore, as a result of studying the shape of the steel plate contact surface of the sliding copper alloy, as the sliding copper alloy, the sliding copper alloy used when welding the steel plates arranged on the same conventional plane, That is, as shown in FIG. 4, it has been found that the same problem as in the case of the backing material can be solved by using a sliding copper alloy whose surface abutting against the steel plate is formed on the same plane.

When the steel plate is arranged so that it bends with the groove back side facing inward, the corners of the steel plate protrude to the groove surface side, and the steel plate contact surface 14 of the sliding copper alloy 4 The corner 19 can be brought into contact with the surface near the end of the steel plate as shown in FIG. Thereby, it is possible to prevent the molten metal from leaking from between the steel plate 1 and the sliding copper metal 4 similarly to the backing material.
In this way, it is not necessary to prepare a corresponding sliding copper alloy for welded joints having different bending angles θw, which is economically advantageous.

  The above is the basic aspect of the backing material and the sliding copper metal used for electrogas arc welding of the welded joint bent with the groove back surface inside, but a more preferable aspect will be described.

In vertical electrogas arc welding, it is common to form a back bead using a ceramic back material that can be easily peeled off from the back bead after welding. Even if the backing material is used, a good back bead can be formed as in the case of ceramics.
Copper backing material is economical because it can be used repeatedly, but it is very heavy and water cooling holes are often provided inside the backing material so that cooling water needs to be drawn in. There are drawbacks. On the other hand, since the ceramic backing material is lighter than the copper backing material, it has good workability and can be used more suitably.
If the backing material is made of steel, the steel backing material and the base material are welded, leaving the backing material as it is, but the gap between the steel backing material and the base material steel plate is subject to fatigue failure. Since it can be a starting point, it cannot be used depending on the structure.

In the above description, the example in which the backing material is brought into contact with the steel plate without using the glass tape is shown. However, the use of the glass tape is preferable because the bead surface becomes smooth. Further, there is a mistake in the steel plates to be abutted, and leakage of molten metal can be prevented to some extent when a gap is formed between the steel plate and the backing material.
In the present invention, a backing material having a shape of θw−28 degrees ≦ θb ≦ θw−2 degrees is used. For this reason, the molten metal is prevented from leaking by contacting the corners of the concave portion 17 for back bead surplus with the steel plate surface. However, when the angle θb becomes smaller than θw, Since metal easily leaks, leakage can be prevented more effectively by using glass tape.

  Regarding the electrogas arc welding method premised on the present invention, the welding conditions such as the welding conditions and the condition of the consumable electrode (welding wire) to be used may be ordinary conditions, and specific conditions are not required. As the welding wire to be used, a flux-cored wire is preferable. Solid wire can also be welded, but by using a flux-cored wire, the slag generated during welding can smooth the surface bead appearance.

  Although the present invention is configured as described above, further examples will be presented below to further explain the feasibility and effects of the present invention.

  Two steel plates shown in Table 2 were bent at the design value θw so as to have a groove shape as shown in Table 2, and butt-arranged, and a weld specimen No. 1 having a weld line length of 1 m. 1 to 20 were prepared, and welded specimen Nos. 1 to 10 is set with a fixed backing material A with θb = θw. In 11 to 20, fixed backing material B with θb = θw−3 degrees was set. The wire used was JIS Z 3319 YFEG-11C (wire diameter 1.6 mm). Next, the sliding copper alloy having a surface abutting against the steel plate of the sliding copper alloy shown in FIG. 4 is pressed against the groove front side of each welded test piece, and welding shown in Table 3 is performed. Electrogas arc welding was performed under the conditions. After welding, the measured bending angle θwa of each specimen was measured, and the difference between θwa and θb and the situation of the back bead were examined.

  The results are shown in Table 4 and Table 5. When the fixed backing material A was used, when θb> θwa, that is, (θb−θwa) ≧ 0 degrees, an overlap was observed on the back bead. . On the other hand, when the fixed backing material B was used, no overlap of the back bead was observed in any case.

  It is possible to provide a suitable welding method for producing a large cylindrical body by sequentially butt welding long plate materials, and can meet the demand for a large cylindrical body, so the industrial applicability is great. .

DESCRIPTION OF SYMBOLS 1 Steel plate 2 Groove 3 Backing material 4 Water cooling sliding copper metal 5 Welding torch 6 Shielding gas hood 7 Welding wire 8 Molten pool 9 Weld metal 10 Molten slag 11 Pipe for cooling water supply 12 Pipe 13 for shielding gas supply 13 Sliding Copper bead forming groove 13
14 Abutting surface of sliding copper alloy to steel plate 15 Glass tape 16 Opposite surface of backing material facing steel plate 17 Concave portion for back bead overlay 18 Corner portion of concave portion 19 19 Abutting of sliding copper alloy Corner of face

Claims (6)

A vertical butt welded joint in which a steel plate, which is a material to be welded, is bent in a chevron shape with an angle θw of 140 to 170 ° with the groove back surface inside the welding line as an axis, In an electrogas arc welding method in which a fixed backing material is arranged on the side, a water-cooled sliding copper alloy is arranged on the surface side, and welding is performed using a consumable electrode
The fixed backing material is arranged and welded so that the inner angle θb of the surface facing the steel plate of the fixed backing material is formed between (θw−28) degrees and (θw−2) degrees. Electrogas arc welding method.   The electrogas arc welding method according to claim 1, wherein the fixed backing material is made of ceramics.   The electrogas arc welding method according to claim 1, wherein the fixed backing material is made of copper.   The electrogas arc welding method according to any one of claims 1 to 3, wherein a glass tape is disposed between a steel plate surface and the fixed backing material.   The said water-cooling sliding copper metal | plating gold | metal | money arrange | positioned at a groove front side uses the gold | metal | money in which the surface contact | abutted to a steel plate surface was formed on the same plane. The electrogas arc welding method as described.   The electrogas arc welding method according to claim 1, wherein the consumable electrode is a flux-cored wire.

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