JPH0994658A - One side butt welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly efficient gas shield arc one side welding by preventing cracks at the high temperature. SOLUTION: A high speed rotation arc one side butt welding method having the feature where the shade of the groove 3 is formed in V type or Y type, the root gap is made at zero, a backing metal 4 is installed on the back face of the groove, the size of welding wire is 2.0 to 3.2mm, the welding current is 500 to 1,500A, and the number of rotation of arc is 3 to 100Hz is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-sided butt welding method for joining single plate members in a bridge or ship building process.

[0002]

2. Description of the Related Art Conventionally, so-called plate joint welding, which connects single plate members to each other in the process of building ships and bridges, has been mostly performed by double-sided or single-sided butt welding by submerged arc welding.

In submerged arc welding, since the arc is submerged in the flux and the welding progresses, the flux is kept stable by the action of the flux even if a large current is passed, so that the melting rate of the welding wire is increased. This is because the features are that it can be made very large, high-efficiency welding can be performed, and that the molten metal is covered with slag and solidifies, so that a good weld bead can be obtained.

[0004]

In recent years, it is necessary to introduce a welding robot in order to save labor. From the viewpoint of operability, welding robots are mainly gas shielded arc welding such as carbon dioxide arc welding and MAG welding.

Therefore, from the viewpoint of labor saving, it has been desired to establish a welding method capable of efficiently carrying out single-sided butt welding using gas shielded arc welding, which is easy to realize a robot for welding.

However, if single-sided butt welding is performed by gas shield arc welding, hot cracking due to the difference in solidification rate of the molten metal is prevented, and the molten metal is sufficiently melted into the back surface to form a good back bead. It is desirable to have a large root gap in order to be able to do so.

As a result, the larger the root gap, the larger the cross-sectional area of welding and the lower the welding speed. Therefore, there is a problem that the welding efficiency is inferior to that of submerged arc welding.

Further, when welding a length of 1 m or more, it is necessary to restrain the groove shape from being deformed by welding heat. However, if the root gap is large, tack welding becomes difficult, and There is no way to restrain it. Therefore, if a method of restraining the material to be welded by straddling the groove with a U-shaped jig called a strong back is adopted, the strong back hinders the automation and efficiency of welding work. There is also the problem of being lost.

A single-sided butt welding method by gas shielded arc welding using a so-called high-speed rotating arc welding method, in which an arc is welded while rotating at a high speed, is disclosed in Japanese Patent Laid-Open No. 2008870/1992. Compared with the method of swinging the normal arc to rotate the arc at a high speed, even if the welding speed is increased, uneven melting and discontinuity of the weld bead do not occur, so relatively efficient welding work can be performed It is a thing. However, this method is premised on using a welding wire having an outer diameter of 0.8 to 1.6 mm which is commonly used in gas shielded arc welding such as carbon dioxide arc welding or MAG welding and is generally commercially available and easily available. Therefore, if the welding current is increased so that sufficient penetration can be obtained even if the welding speed is further increased, the welding wire will be over-melted, and high-temperature cracks are likely to occur due to hot cracking due to solidification shrinkage. It becomes a shape. Further, if the welding current is reduced in order to suppress the height of the weld bead, sufficient heat input cannot be obtained, the penetration becomes shallow, and a good back bead is not formed. As a result, there is a limit to the improvement of the welding speed, and there is a problem that the welding efficiency is far inferior to that of submerged arc welding.

The present invention has been made to solve the above-mentioned problems, and provides a highly efficient single-sided butt welding method using gas shielded arc welding.

[0011]

The first means for solving the above problems is to perform one-sided butt welding by gas shield arc welding, in which the groove shape is V type or Y type and the root gap is in the standard state. Zero and welding wire outer diameter is 2.0
The single-sided butt welding method is characterized in that the arc is performed at a high speed of 3.2 mm, a welding current of 500 to 1500 A, and a rotational speed of 30 to 100 Hz.

Since the arc is rotated at a high speed of 30 Hz or more, due to the dispersion effect of the arc, sufficient penetration can be obtained and a good back bead can be formed even if the root gap is set to zero in the standard state. As a result, the welding cross-sectional area is small, and efficient welding can be performed.

When the rotation speed of the arc exceeds 100 Hz, the centrifugal force becomes excessively large, the transfer of droplets becomes unstable, and spatter increases, so the frequency was limited to 100 Hz or less.

By using a welding wire having a large outer diameter of 2.0 mm or more as the welding wire, even if the welding current is increased so that sufficient penetration can be obtained even at the welding speed equivalent to that of submerged arc welding, Since the welding wire does not melt too much, the weld bead shape is appropriate without the risk of hot cracking.

If the outer diameter of the wire exceeds 3.2 mm, the feedability of the welding wire deteriorates, so the wire diameter is limited to 3.2 mm or less.

By setting the welding current to 500 A or more, sufficient penetration can be obtained even at a welding speed equivalent to that of submerged arc welding, and a good back bead is formed.

However, if the welding current exceeds 1500 A, the heat input becomes unnecessarily large and it is not efficient.
It is limited to 0A or less.

A second means for solving the above-mentioned problems is characterized in that, in the one-side butt welding method described in the first means, welding is performed by forming an in-plane tack on the groove bottom. is there.

As described above, good welding work can be performed even if the root gap is set to zero in the standard state, so that it becomes possible to form the in-plane tack in the groove. And
Even in the in-plane temporary attachment portion, sufficient penetration can be obtained by the high welding current welding described in the first means. Therefore, when welding a long length of 1 m or more, it is possible to easily restrain the material to be welded by the in-plane tacking, and it is possible to eliminate obstacles such as strongback which are an obstacle to automation.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a front view according to an embodiment of the present invention, wherein 1 and 2 are single-sided butts in which the root gap is zero and the groove 3 is formed in a V shape. A welded material to be welded, and 4 is a backing material made of ceramics, copper or the like, which is in contact with the back surface of the groove 3. 5 is a welding torch that rotates at high speed, 6 is a welding wire (consumable electrode)
Then, the inside of the groove 3 is rotated at a high speed within the range of the dotted line.

2 (front view) and FIG. 3 (plan view of FIG. 2) show an in-plane temporary bead 7 placed in the groove 3.
As an example, the in-plane temporary bead 7 has a height (H) of about 5 m.
m, the length (L) of the in-plane temporary bead 7 was 50 mm, and the pitch (P) of the in-plane temporary bead 7 was 300 mm. The in-plane tacky beads 7 are manually or semi-automatically welded prior to the single-sided butt welding.

As shown in the front view of FIG. 4, if the iron powder 8 is dispersed in the groove 3 in the welding length direction, the groove 3 can be formed during welding.
Since the processing accuracy of is poor, a good back bead can be formed even if the root gap is opened. Further, there is an effect that the back bead width of the in-plane temporary bead portion and other back bead widths become constant.
The spraying height is about 5 mm.

The single-sided butt welding of the present invention was carried out by the following examples, and good results were obtained. Example 1 (1) Welding material: Mild steel material 50 kg class (plate thickness 16 mm) (2) Groove shape: V groove 40 ° (3) Gap: 0 mm (standard) (4) Backing material: Ceramics (5) Welding wire: Metal cored 2.0 mmφ (6) Shielding gas: CO ₂ 100% (7) Welding method: First layer, high-speed rotating arc welding Rotation diameter: 4 mm Rotation speed: 50 Hz (8) First layer welding current: 600 A (9) ) Welding speed: 40 cm / min

Example 2 (1) Welding material: Mild steel material 50 kg class (plate thickness 20 mm) (2) Groove shape: V groove 50 ° (3) Gap: 0 mm (standard) (4) Backing material: Copper Backing (5) In-plane temporary attachment: (H) 5 mm, (L) 50 mm,
(P) 300 mm (6) Welding wire: Metal cored wire 2.5 mm
φ (7) Shield gas: CO ₂ 100% (8) Welding method: High speed rotating arc welding Rotating diameter: 4 mm Rotating speed: 50 Hz (9) Welding current: 600 A (10) Welding speed: 40 cm / min

In the first embodiment, the welding efficiency is
It was 5.4 minutes / m in 2 passes, and in Example 2, it was 7.4 minutes / m in 3 passes. This efficiency is comparable to conventional submerged arc welding,
There were no hot cracks.

[0026]

EFFECTS OF THE INVENTION The single-sided butt welding of the present invention enables high-efficiency gas-shielded arc single-sided butt welding without high-temperature cracking, which saves labor for plate joint welding and realizes a welding robot. It has become possible to plan.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is a front view showing another embodiment of the present invention.

FIG. 3 is a plan view of FIG. 2;

FIG. 4 is a front view showing another embodiment of the present invention.

[Explanation of symbols]

 1, 2 Welded material 3 Bevel 4 Backing material 5 Welding torch 6 Welding wire 7 In-plane temporary bead 8 Iron powder

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B23K 33/00 B23K 33/00 Z

Claims (2)

[Claims] 1. When performing one-sided butt welding by gas shield arc welding, the groove shape is V type or Y type, the root gap is set to zero in the standard state, and the welding wire outer diameter is 2.0.
A single-sided butt welding method, wherein the welding current is 500 mm to 3.2 mm, the welding current is 500 to 1500 A, and the arc is rotated at high speed at a rotation speed of 30 to 100 Hz. 2. The one-side butt welding method according to claim 1, wherein an in-plane tack is formed on the bottom of the groove to perform welding.