JP2001001169A - Electro gas welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a deterioration of quality of a heat-affected zone of a base material by welding the base material with a multi-layer welding method to a specified thickness, welding one part of a remaining groove, which is divided into two parts, with a multi-layer welding method, then welding the other part of the groove with a multi-layer welding method. SOLUTION: A fixed backing member 3 is fixed on the rear of a base material 1 in a manner that the V-shaped grooves 2 of the base material 1 are butted, a water- cooled copper strap member 41 is fixed to the surface of the base material 1, and a layer 51 is welded. This welding is repeated for plural layers until nearly 2/3 of the thickness of the base material 1. Then a water-cooled copper strap member 43 used for welding a layer 53 is removed, a fixed shoe 6 which has a form dividing a remaining two layers into two parts is fixed to a V-shaped groove 2, a water-cooled copper strap member 44a, having a protruded part corresponding to the form of an upper layer of two layers divided into two parts on which the shoe is not fixed, is fixed, and a layer 54a which is a part of a layer 54 divided into two parts is welded. Then the water-cooled copper strap member 44a is replaced with a water-cooled copper strap member 45 whose groove side is flat, and a layer 55a which is a part of a layer 55 divided into two parts is welded. Then layers 54b and 55b are welded in the same way.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrogas welding method for joining steel structures such as bridges, and more particularly to reducing welding heat input to prevent a heat-affected zone of a base material from becoming brittle. It is about.

[0002]

2. Description of the Related Art For example, a box girder is used as a main girder in a streamlined design bridge. The box girder has a box-shaped cross section made of a plate material to increase bending rigidity and torsional rigidity and acts integrally as a whole against external force, which is extremely advantageous for a bridge between long supports and a curved girder. In recent years, box girders have become longer spans, and the plate materials used tend to be thicker.
It is nearly 00 mm, and the girder height is about 3000 mm. When joining this box girder, it is difficult to join bolts with splice plates (seam plates) used in conventional bridges, and on-site welding is indispensable.

[0003] Electrogas welding is widely used for welding steel structures such as box girders. In the electrogas welding, as shown in FIG. 2, the molten metal 7 is surrounded between the groove surface of the base material 1 and the water-cooled copper pad 4, and the welding wire 8 is continuously and automatically supplied with the water-cooled copper pad 4. Is moved upward to perform vertical welding. When a box girder or the like having a large plate thickness is joined by this electrogas welding, several passes of multi-layer welding are performed using a V-shaped groove.

[0004]

When joining a base material having a large thickness such as a box girder, it is necessary to reduce the number of welding layers in order to suppress the deterioration of the heat-affected zone of the base material due to welding heat input. It is necessary to increase and reduce the welding heat input for each layer. However, even if the number of welding layers is increased, when the V-shaped groove is used because the plate thickness is as large as about 100 mm, the groove cross-sectional area of the upper layer cannot be reduced, and the welding heat input can be reduced in the upper layer. It is difficult, and there is a possibility that the material is deteriorated in the heat-affected zone of the base material.

An object of the present invention is to provide an electro-gas welding method which can improve the disadvantages and reduce the heat input to each layer to suppress the deterioration of the heat-affected zone of the base material. It is the purpose.

[0006]

According to the electrogas welding method according to the present invention, after welding to a thickness of about 2/3 of the base material by multi-layer welding, the remaining groove cross-sectional area is divided into two parts. It is characterized in that after welding one of them with a multilayer overlay, the other is welded with a multilayer overlay.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the electrogas welding method according to the present invention, when a base material having a large thickness is welded with, for example, five layers using a V-shaped groove, one to three layers are formed by ordinary water-cooled copper. Weld using a pad. After welding up to 3 layers, the remaining 2
The V-shaped groove is divided into two parts by using a fixed shoe with the layer divided into two parts left and right to reduce the sectional area of the upper layer, and one of the divided four layers and five layers is welded. The fourth and fifth layers are welded to reduce welding heat input in the upper layer of the V-shaped groove.

[0008]

FIG. 1 is a construction process diagram of an embodiment of the present invention. As shown in FIG. 1A, a fixed backing material 3 is fixed to the back surface of the base material 1 in a state where the V-shaped groove 2 of the base material 1 is abutted, and conventionally used on the surface of the base material 1. A water-cooled copper pad 41 of a sliding type is attached. In this state, one V-shaped groove 2
The layer 51 is welded. This conventionally used multi-layer welding is performed in a plurality of layers up to a thickness of about ／ of the base material 1. For example, when the base material 1 having a thickness of 75 mm is to be welded in five layers, as shown in FIG. After welding to the three layers 53, the water-cooled copper pad 43 used for welding the three layers 53 is removed, and as shown in FIG. 1 (c), the fixed shoe 6 in which the remaining two layers are divided into two parts is V-shaped. A water-cooled copper pad 44a having a protrusion corresponding to the shape of the upper layer of the two divided two layers to which the fixing shoe 6 is not attached is attached to the groove 2, and the four layers 54
One of the divided layers 54a is welded. Then, FIG.
As shown in (d), the water-cooled copper pad 44a is replaced with a water-cooled copper pad 45 having a flat groove side, and one of the five layers 55 is divided into two and welded. One of the two divided layers 55
After the welding of (a) is completed, as shown in FIG. 1 (e), the water-cooled copper pad 45 and the fixing shoe 6 are removed, and the water-cooled copper having a protrusion corresponding to the shape of the upper layer of the remaining two layers divided into two. The backing plate 44b is attached, and the remaining four divided layers 54b are welded. After that, as shown in FIG. 1 (f), the water-cooled copper pad 44b is replaced with a water-cooled copper pad 45 and the remaining five layers 5
5b is welded.

When the base material 1 having a large thickness is welded in this way, the sectional area of the upper layer of the V-shaped groove 2 is divided into two and reduced and divided and welded. Weld heat input in the upper layer can be reduced.

[0010]

As described above, according to the present invention, when a base material having a large thickness is welded by multi-layer welding using a V-shaped groove, the thickness of the multi-layer build is reduced to approximately ／ of the thickness of the base material. After welding,
The remaining groove cross-section was divided into two parts, and one of the two parts was welded with a multi-layer fillet, and the other was welded with a multi-layer fillet. Heat input can be reduced, and material deterioration in the heat-affected zone of the base material can be suppressed.

[Brief description of the drawings]

FIG. 1 is a construction process diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram showing electrogas welding.

[Description of Signs] 1 Base material 2 V-shaped groove 3 Fixed backing material 4, 41, 43, 44a, 44b, 45 Water-cooled copper plate 6 Fixed shoe

Claims (1)

[Claims] In an electrogas welding method for joining a base metal around a molten metal between a groove surface of the base metal and a water-cooled copper plate, the base metal is welded by multi-layer welding to a thickness of about 2/3 of the base metal. Thereafter, the remaining groove cross-sectional area is divided into two parts, and one of the two divided parts is welded with a multi-layer pile, and the other is welded with a multi-layer pile.