JP2000061665A - Consumable nozzle type electro-slag welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably weld with suppressing deterioration of a material property of a heat affected part due to heat input by using a consumable nozzle not covered with flux and making at least one of copper backings slidable so as to permit narrow gap welding as well as to directly monitor a molten slag pool. SOLUTION: A welding part is encircled with a water cooling type sliding type copper backing 3A and a fixed type copper backing 3B, a welding wire 6 is supplied into a molten slag 1, while ascending the sliding type copper backing 3A, base materials 7 are welded each other by the electric resistance heat of the molten slag due to energizing. A consumable nozzle 9, which is not covered with flux and of a small diameter, is used, narrow gap welding is made possible, heat input is decreased to suppress material deterioration of a heat affected zone. One side is the sliding type copper backing 3A, the molten slag 1 pool can be directly monitored, the supply speed, etc., of the welding wire is adjusted so as to make its depth appropriate, thus, the contact between the consumable nozzle 9 not covered with flux and the base material 7 can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a consumable nozzle type electroslag welding method, and in particular, by enabling narrow groove welding, deterioration of material characteristics of a heat affected zone due to heat input can be suppressed. Moreover, the present invention relates to a consumable-nozzle electroslag welding method that enables stable welding by directly monitoring the molten slag bath.

[0002]

2. Description of the Related Art In recent years, for example, in order to reduce the construction cost of a bridge, attention has been paid to a small number of bridges for the purpose of reducing the number of members constituting the bridge. A small number of major bridges use large I-section steel structural materials as the main structure, and the flange thickness is 100 at maximum.
The height of the web is about 3000 mm, and the height of the web is about 3000 mm by the consumable nozzle electroslag welding method. Therefore, it is difficult to connect the bolts by the splice (joint plate) used in the conventional bridge. Therefore, in building such a bridge, on-site welding of I-shaped steel structural members is essential.

Incidentally, one of the on-site weldings of I-shaped cross-section steel structural materials is a so-called north scallop method in which a scallop is not formed on a web. This method is a method of welding the web through the upper and lower flanges, and has the advantage that a joint with a defect-free cross section can be obtained as compared with the case of the scallop method of forming a scallop on the web, while the lower flange is It has the disadvantage that upward welding is indispensable.

As a welding method for large-sized I-section steel structural materials,
A non-consumable nozzle type electroslag welding method is considered.
In this non-consumable nozzle electroslag welding method, as shown in FIG. 2, the welded portion is surrounded by a pair of water-cooled copper pads 3 to prevent the molten slag 1 and the molten metal 2 from flowing out of the welded portion, and a flux 4 is used. Together with continuously supplying the welding wire 6 into the molten slag 1 bath through the non-consumable nozzle 5,
Then, while raising the pair of copper patches 3 together, the welding wire 6, the molten slag 1 and the base material 7 are melted by the electric resistance heat of the molten slag 1 by the energization of the welding wire 6, the molten slag 1 and the base material 7, The base materials 7 are welded to each other.

However, the above-mentioned non-consumable nozzle type electroslag welding method is not suitable for the on-site welding of the above-mentioned large-sized I-section steel structural material because the welding equipment becomes large-scale.

Therefore, there is a consumable-nozzle type electroslag welding method as a welding method in which the non-consumable-nozzle type electroslag welding is made simpler and lighter. This consumable-nozzle electroslag welding method, as shown in FIG. 3, surrounds the welded portion with a pair of water-cooled copper pads 3 so that the molten slag 1 and the molten metal 2 do not flow out of the welded portion, and is made of steel. A welding wire 6 is continuously supplied into a bath of a molten slag 1 through a consumable nozzle 8 formed by coating a surface of a pipe with a flux, and a molten slag is generated by energizing the welding wire 6, the molten slag 1 and a base metal 7. The consumable nozzle 9, the welding wire 6 and the base material 7 are melted by the electric resistance heat 1 to weld the base materials 7 to each other.

In the consumable nozzle type electroslag welding method described above, the copper pad 3 is usually fixed to the base metal 7 over the entire welding length. If the welding length exceeds 3000 mm,
A copper pad having a length of about 600 mm is cottered in two stages, and the lower copper pad and the lower copper pad are sequentially replaced in accordance with the progress of welding.

[0008]

However, the above-mentioned conventional consumable nozzle type electroslag welding method has the following problems. In order to suppress the deterioration of the material properties of the heat-affected zone due to heat input, it is necessary to reduce the heat input as much as possible with a narrow groove, but the consumable nozzle consists of a steel pipe coated with flux. The diameter is 10 to 1
2mmφ and thick. Therefore, a narrow groove of about 16 mm cannot be formed. Even though the copper pad 3 is divided, one copper pad 3
When the length is 600 mm, the molten slag 1 cannot be directly monitored. Therefore, as in the case of the fixed copper pad, the operator determines the depth of the molten slag 1 bath from the boiling sound of the molten slag 1, the sound and light of the arc, and the red heat state near the welded portion, and determines the depth of the molten slag 1. The feed rate of the welding wire 6 and the flux 4 so that the depth of one bath is properly maintained.
Although the welding conditions such as the supply amount of are adjusted, it requires a certain amount of skill to be able to make an appropriate judgment, and judgment errors due to individual differences are likely to occur.

Therefore, the object of the present invention is to enable the narrow groove welding to suppress the deterioration of the material characteristics of the heat-affected zone due to the heat input, and further to directly monitor the molten slag bath. By providing a consumable nozzle type electroslag welding method, stable welding can be achieved.

[0010]

The invention according to claim 1 is
In the method of butt welding steel structure members by consumable nozzle type electroslag welding method, use one that is not coated with flux as a consumable nozzle, and make at least one of copper pads slidable, thus It is characterized in that it enables narrow groove welding and enables direct monitoring of the molten slag bath.

The invention according to claim 2 is characterized in that an electrically insulating tape is wound around the outer surface of the consumable nozzle.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the consumable nozzle type electroslag welding method of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic partial sectional view showing a welding method of the present invention. In FIG. 1, 1 is molten slag, 2 is
Are molten metal under the molten slag 1, and 3A and 3B are a pair of water-cooled copper bars surrounding the welded portion so that the molten slag 1 and the molten metal 2 do not flow out from the welded portion. Is a sliding type, and the other copper pad 3B is a fixed type. Both copper pads 3A and 3B may be of sliding type. 4 is the flux supplied to the molten slag 1 bath,
6 is a welding wire, 7 is a base material, and 9 is a consumable nozzle made of a steel pipe through which the welding wire 6 is passed.

Since the outer surface of the consumable nozzle 9 is not covered with flux, the diameter of the consumable nozzle 9 is reduced by the thickness of the flux. The consumable nozzle 9
By winding an electrically insulating tape such as a silicon tape around the outer surface of the above, it is possible to reliably prevent the consumable nozzle 9 from electrically contacting the base material 7 during welding.

According to the welding method of the present invention configured as described above, the base materials 7 are welded to each other as follows. The welded portion is surrounded by water-cooled copper patches 3A and 3B, the welding wire 6 is continuously supplied into the molten slag 1 bath, and the copper wire 3A on one side is raised while the welding wire 6 and the molten slag 1 are added. And the electrical resistance heat of the molten slag 1 due to the energization of the base material 7, the consumption nozzle 9,
The welding wire 6 and the base material 7 are melted. As a result, the base materials 7 are welded to each other.

According to the present invention, since the outer surface of the consumable nozzle 8 is not coated with the flux, the diameter of the consumable nozzle 8 can be reduced accordingly. Therefore, narrow groove welding becomes possible. Therefore, since the amount of heat input can be reduced, the deterioration of the material characteristics of the heat-affected zone due to heat input can be suppressed.

Further, according to the present invention, the one copper pad 3A is of the sliding type and the other copper pad 3B is of the fixed type, so that one copper pad 3A of the sliding type can be used. One bath of molten slag can easily be monitored directly. Therefore,
The welding conditions such as the supply speed of the welding wire 6 and the supply amount of the flux 4 can be easily adjusted so that the depth of the molten slag 1 bath becomes an appropriate depth, and furthermore, the consumable nozzle in the groove. Since the position of 9 can be easily confirmed from the outside, the consumable nozzle 9 can be prevented from coming into contact with the base material 7.

[0018]

EXAMPLES Next, the welding method of the present invention will be described in more detail by way of examples. 1000m long consisting of SM570
Steel sheet having a thickness of m and a thickness of 19 mm was subjected to I-groove butt welding. The welding wire used at this time was 2.4 m on the market.
The wire was a solid wire having a diameter of m, and the consumable nozzle was a commercially available steel pipe having an outer diameter of 8 mmφ, which was not coated with flux. A silicone tape was wrapped around the outer surface of the consumable nozzle to prevent electrical contact with the base material.

The groove width was set to a narrow groove of 16 mm in consideration of the outer diameter 8 mmφ of the consumable nozzle. One of the pair of water-cooled copper bars is a sliding type and the length is 1
It was set to 50 mm. The sliding copper pad was made slidable by fixing it to a truck running on a rail attached to the base material. The other copper pad is fixed and the length is 60
It was set to 0 mm.

As a result, narrow groove welding is possible, and since the molten slag bath can be directly monitored, welding current: 370 A, welding voltage: 35 V, welding speed: 3.5 c
m / min. Welding heat input (Q) is 220k under the welding conditions
A stable molten slag bath was obtained with a low heat input of j / cm.

As is apparent from this embodiment, the welding method of the present invention allows the above-mentioned large-sized I-section steel structural members to be joined together without causing deterioration of the material characteristics of the heat-affected zone due to heat input, and It was found that stable welding was possible. When welding a large-sized I-section steel structure material by the welding method of the present invention, both the scallop method and the north scallop method described above can be applied.

[0022]

As described above, according to the present invention, in the method of butt welding steel structural members to each other by the consumable nozzle type electroslag welding method, a consumable nozzle which is not coated with flux is used. As a result, narrow groove welding is possible, so deterioration of the material properties of the heat-affected zone due to heat input can be suppressed, and at least one of the copper pads can be slid to allow melting. Since the slag bath can be directly monitored, it has a useful effect that stable welding can be performed.

[Brief description of drawings]

FIG. 1 is a partially cutaway schematic perspective view showing a consumable nozzle type electroslag welding method of the present invention.

FIG. 2 is a partially cutaway schematic perspective view showing a conventional non-consumable nozzle type electroslag welding method.

FIG. 3 is a partially cutaway schematic perspective view showing a conventional consumable nozzle type electroslag welding method.

[Explanation of symbols]

1: Molten slag 2: Molten metal 3: Copper pad 3A: Sliding copper pad 3B: Fixed copper pad 4: Flux 5: Non-consumable nozzle 6: Welding wire 7: Base material 8: Consumable nozzle 9: Consumable nozzle not coated with flux

Claims (2)

[Claims] 1. A method of butt-welding steel structural members to each other by a consumable nozzle electroslag welding method, wherein a consumable nozzle not coated with flux is used, and at least one of water-cooled copper plates is slid. A consumable-nozzle electroslag welding method that is movable and thus enables narrow groove welding and direct monitoring of the molten slag bath. 2. The consumable nozzle electroslag welding method according to claim 1, wherein an electrical insulating tape is wrapped around the outer surface of the consumable nozzle.