JPH10128539A - Gma welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the repair and slag removing work of a weld zone through one-layer one-pass welding and to prevent the occurrence of detect in the GMA(gas metal arc) welding method applicable to one side butt welding joint of a large structure. SOLUTION: By traveling a welding torch 4 at the groove part of a material 7 to be welded, a weld bead 6 is formed by an arc point 5. A weir copper plate 1 of taper shape for preceding molten meal is inserted in the groove at front of the torch 4, a jig 2 for traveling the copper plate is mounted on an upper face of the copper plate 1, the copper plate 1 is traveled in the welding direction by a motor, etc. Further, the copper plate 1 is cooled with cooling water by a copper plate cooling tube 3. The copper plate 1 is traveled at the same speed as the welding torch 4 travels, welding is bone in one layer one pass, the processing molten metal of fused metal is suppressed, thus, a good back bead is formed even by one layer one-pass, thus, working of repair, slag removing, etc., is eliminated, as a result, defect is not caused.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to GMA (Gas Meta) applied to the welding of single-sided downward butt welded joints of large structures.
l Arc) Welding method.

[0002]

2. Description of the Related Art GMA welding is a gas metal arc welding method in which an active or inert gas is used as a shielding gas, such as CO ₂ or MIG welding. FIG.
5 to 5 outline the welding method.

FIG. 3 is a perspective view of a conventional GMA welding method, and FIG. 4 shows a welded portion by the conventional GMA welding method.
Is a longitudinal sectional view, and (b) is a transverse sectional view. FIG. 5 is a longitudinal sectional view showing a weld metal and a predeposited metal at a welded portion when one pass per layer is performed by a conventional GMA welding method.

In FIG. 3, 4 is a welding torch, 5 is an arc point, 6 is a welding bead, 7 is a material to be welded, 8 is a backing material, 9 is a backing material.
Is a reinforcing material such as a longe. In the conventional GMA welding method configured as described above, in the case where the material 7 to be welded is a thick plate, multi-layer multi-pass welding is performed, and the plate thickness is approximately 20 m.
m, the welding time of about 10m is required by the welder 4
It takes about 3 hours for ~ 5 people.

In FIG. 4, reference numeral 010 denotes a deposited metal;
First layer 010-1, second layer 010-2, third layer 010-
3, consisting of four layers, a finishing layer 010-4. In the welding operation, after attaching the backing material 8 to the back surface of the material 7 to be welded, the first layer 010
After forming a good back bead at -1, until the finish layer 010-4,
The construction is about 4 layers and 4 passes with a thickness of about 20mm.

FIG. 5 shows an example in which this multi-layer, multi-pass welding is performed in a single-layer pass. In FIG. 5, reference numeral 11 denotes a molten metal preceding molten metal (hereinafter abbreviated as “preceding molten metal”). If this is attempted, a favorable back bead cannot be obtained because the preceding hot water 11 is generated. In addition, poor fusion occurs. Therefore, in order to prevent a welding defect between layers while forming a good back bead, multilayer multi-pass welding is performed.

[0007]

SUMMARY OF THE INVENTION Conventional multi-layer multi-pass GM
In the A-welding, the welding current for the first layer is set at about 200 A in order to form a good back bead, and the welding current for the first and subsequent layers is set at about 300 A. However, the following problems occur.

(1) Welding efficiency is poor due to multi-pass multi-pass welding with low welding current. (2) In multi-pass multi-pass welding, the seam of the weld bead increases, and repair for removing cracks or the like generated in the crater portion of the front weld bead is required.

(3) Before welding from the first layer to the finish layer, it is necessary to perform a slag removal operation using a can-can hammer or an air-seaper to prevent welding defects such as poor fusion.

(4) If an attempt is made to increase the welding current and lower the welding speed to reduce the number of layers, the molten metal takes precedence and defects in the back bead shape and welding defects are likely to occur.

From the above, conventionally, welding work requires human labor, and it has been difficult to improve welding work efficiency.

[0012]

According to the present invention, there is provided a GM for performing one-side welding while moving a welding torch along a groove of a material to be welded placed in a horizontal state.
In the A welding method, a weld pool damming copper plate is slidably provided in a groove in front of the welding torch; the copper plate is moved at substantially the same speed as the welding torch, while preventing leading of the molten metal; Provided is a GMA welding method, wherein a material to be welded is welded in one pass per layer.

In the welding method according to the present invention, in order to prevent the molten metal from being preceded by molten metal, a molten pool damming copper plate corresponding to the groove shape is inserted into the groove at the front of the welding torch, and the damping copper plate is moved in the traveling direction. Since it moves at almost the same speed as the welding torch and performs welding while preventing the preceding molten metal, a high current (for example, a plate thickness of about 20
mm, welding current of about 450 A).

Such a damping copper plate may be of a water-cooled type, and its shape is adapted to a groove shape such as a groove angle, but the shape of the lower side of the surface for stopping the preceding hot water is slightly smaller. It is preferable that the taper be formed in accordance with the shape of the groove so that the corner in contact with the groove on the front surface in the welding progress direction is slightly rounded. With these, it is possible to obtain a slippery copper plate with good slip which does not catch even if the groove shape changes.

[0015]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a perspective view showing the construction of a GMA welding method according to one embodiment of the present invention,
FIG. 2 shows a cross section of the welded portion, (a) is a longitudinal sectional view, (b)
Is a cross-sectional view.

In FIG. 1, reference numeral 1 denotes a copper plate for damming the preceding
2 is a copper plate moving jig, 3 is a copper plate cooling tube, 4 is a welding torch, 5 is an arc point, 6 is a weld bead, 7 is a material to be welded, 8 is a backing material for forming a back bead, and 9 is a reinforcement. A material (such as a longe) 10 is a deposited metal.

Next, with reference to FIG. 2, a detailed structure of a main part of an apparatus for performing the above-mentioned GMA welding method will be described. As shown in FIG. 2 (b),
The lower portion is slightly smaller than the groove shape and extends in a tapered shape so that it can be inserted into the groove, and it is preferable that the corners in contact with the groove are rounded. A copper plate moving jig 2 for moving the copper plate 1 in the welding direction is fixed to the upper surface, and a distal end portion is connected to a moving means such as a motor.

A copper plate cooling tube 3 is inserted in a longitudinal direction of the main body of the preceding damming copper plate 1 so that cooling water can flow through the tube 3 to cool the tube.

Next, the welding procedure in the above configuration will be described. First, (1) a backing material 8 for forming a back bead is attached to the groove back surface of the material 7 to be welded. Next, (2) the preceding damming copper plate 1 having a groove shape (groove angle, route interval) is inserted into the groove. (3) After activating the welding torch 4 and starting welding, the pre-bindering copper plate 1 is wound up with wires by a motor or the like provided at the welding end of the material 7 to be welded in accordance with an appropriate welding speed. Move at the same speed. The distance between the damping copper plate 1 and the arc point 5 is about 20 to 2
Weld while maintaining 5mm.

When there is no obstacle such as the reinforcing member 9 on the welding line, the damping copper plate 1 is used by attaching it to a commercially available simple welding cart or the like.

The welding current in the above welding is one layer per layer.
Since the pass welding is used, welding can be performed at a high current of about 450 A with a thickness of about 20 mm. The pre-binder copper plate 1 is connected to a cooling water source with the copper plate cooling tube 3 and cooled by flowing cooling water.

[0022]

As described above, according to the GMA welding method of the present invention, the leading metal generated at the time of high current welding is damped with a molten metal damming copper plate and welded while moving the copper plate. The following effects were obtained.

(1) One downward layer 1 of thick copper plate (about 20 mm)
Pass MAG welding is now possible. (2) It is unnecessary to repair weld bead joints (craters and the like) and remove slag between welded laminations, which occur during multi-pass multi-pass welding. Both joint quality has improved.

(3) In the case of simple automatic welding in combination with a commercially available traveling carriage for welding, more efficient welding can be performed by using two to three vehicles per person.

[Brief description of the drawings]

FIG. 1 is a perspective view of a welding apparatus to which a GMA welding method according to an embodiment of the present invention is applied.

2A and 2B show a GMA welding apparatus according to one embodiment of the present invention, wherein FIG. 2A is a longitudinal sectional view, and FIG. 2B is a transverse sectional view.

FIG. 3 is a perspective view showing an outline of a conventional GMA welding method.

4A and 4B show a cross section of a welded portion by a conventional GMA welding method, in which FIG. 4A is a longitudinal sectional view, and FIG.

FIG. 5 is a vertical cross-sectional view of a welded portion when the conventional GMA welding method is applied in one layer and one pass.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 1 Pre-wet damping copper plate 2 Copper plate moving jig 3 Copper plate cooling tube 4 Welding torch 5 Arc point 6 Weld bead 7 Material to be welded 8 Backing material 10 Weld metal

Claims (1)

[Claims] 1. A GM for performing one-side welding while moving a welding torch along a groove of a material to be welded placed in a horizontal state.
In the A welding method, a weld pool damming copper plate is slidably provided in a groove in front of the welding torch; the copper plate is moved at substantially the same speed as the welding torch, while preventing leading of the molten metal; A GMA welding method, wherein a material to be welded is welded in one layer and one pass.