JP7341937B2 - Electroslag welding method - Google Patents

Description

The present invention relates to an electroslag welding method, and more particularly to an electroslag welding method that can prevent melt leakage during welding and obtain a good weld bead without undercuts.

Electroslag welding involves sandwiching steel plates vertically aligned at a predetermined distance, or steel plates with the end face of one steel plate aligned with the surface of the other steel plate in a T-shape, between water-cooled copper plates or steel plates. Flux is added into the enclosed groove and a consumable or non-consumable power supply nozzle is inserted to continuously supply welding wire. After welding starts, the flux melted by arc heat forms a slag bath, and the melting This is a welding method in which the slag reaches a high temperature due to its own resistance heat generation due to current flowing through it, melts the continuously supplied wire and base metal, and forms molten metal at the bottom of the slag bath. Electroslag welding allows one-pass welding and is more efficient than other welding methods, so it is widely applied in the fields of steel frames and bridges.

FIG. 2 shows conventional electroslag welding. As shown in FIG. 2, a gap is provided between a steel plate 101 and a steel plate 102 that are aligned vertically, and a water-cooled copper plate 103 and a water-cooled copper plate 104 are installed so as to sandwich this gap in the substantially vertical direction. The ends of the steel plate 101 and the steel plate 102 on the water-cooled copper plate 103 side are respectively called a first end 101a and the first end 102a, and the ends of the steel plate 101 and the steel plate 102 on the water-cooled copper plate 104 side are called a second end 101b and a second end, respectively. The ends of the water-cooled copper plates 103 and 104 on the steel plate 101 side are respectively referred to as first ends 103a and 104a, and the ends of the water-cooled copper plates 103 and water-cooled copper plates 104 on the steel plate 102 side are respectively referred to as end portions 102b. In the case of the second end 103b and the second end 104b, the first end 101a and the first end 103a, the first end 102a and the second end 103b, the second end 101b and the first end 104a, A groove 105 is formed by bringing the second end 102b and the second end 104b into contact with each other.

As a result of performing electroslag welding using this groove 105 and conducting various studies, we found that the processed state of the ends of the steel plate 101 and the steel plate 102 at each contact surface where the steel plate 101 and the steel plate 102 and the water-cooled copper plate 103 and the water-cooled copper plate 104 contact each other. If a gap occurs between the contact surfaces of the steel plate 101 and the steel plate 102 and the water-cooled copper plate 103 and the water-cooled copper plate 104 due to the degree of parallelism between the steel plate 101 and the steel plate 102, the degree of pressing of the water-cooled copper plate 103 and the water-cooled copper plate 104, etc., the gap The molten metal in the groove 105 enters the groove, and slag is generated on the surface during solidification. Since this slag is thick, there is a problem in that undercuts occur when the slag is removed. Further, if the gap is large, there is a problem in that molten metal flows into the gap and leakage occurs.

Further, Patent Document 1 discloses a non-consumable nozzle type electroslag welding method that is simple to operate and has high welding efficiency. However, in electroslag welding, which welds vertically butted steel plates together, a groove is formed by combining the steel plate and water-cooled copper plate, but if the groove precision at the edge of the steel plate is poor, the steel plate and water-cooled copper plate will not adhere uniformly. If the test specimen is deformed during welding, a gap may be created between the steel plate and the water-cooled copper plate, causing molten metal to flow down (hereinafter referred to as molten metal leakage), resulting in a defective bead shape. There was a problem with becoming.

Regarding a method to improve this problem, Patent Document 2 discloses that by placing a thermally expandable refractory material on the contact surface between the steel pipe member and the diaphragm, the backing material is placed between the steel pipe member and the diaphragm. A method is disclosed in which, during welding, a thermally expandable refractory material expands to close the gap between a steel pipe member and a backing material to prevent molten metal from leaking. However, the method described in Patent Document 2 is a method for preventing melt leakage during electroslag welding between a steel pipe member and a diaphragm, and the method described in Patent Document 2 is a method for preventing melt leakage during electroslag welding between a steel pipe member and a diaphragm. Slag welding has a problem in that it is difficult to completely close the gap between the contact surfaces, and a sufficient effect cannot be obtained.

Further, Patent Document 3 discloses a method for manufacturing a diaphragm that prevents leakage of hot water during electroslag by providing protrusions at both ends of the end face of the diaphragm that comes into contact with a steel pipe member. However, electroslag welding, which involves welding within a groove surrounded by a steel plate and a water-cooled copper plate, has the problem that it is difficult to provide protrusions on the end face of the entire length of the steel plate, and a sufficient effect cannot be obtained.

Japanese Patent Application Publication No. 8-10969 Japanese Patent Application Publication No. 7-229243 Japanese Patent Application Publication No. 2004-351438

The present invention has been devised in view of the above-mentioned problems, and is an electroslag welding method that can prevent melt leakage during welding and provide a good weld bead without undercuts. The purpose is to provide a method.

The gist of the present invention is to abut the steel plates vertically with a predetermined gap between them, sandwich the gap between water-cooled copper plates, and weld the inside of the groove surrounded by the steel plate and the water-cooled copper plate. In the slag welding method, the water-cooled copper plate is arranged so that the groove is surrounded by a groove recessed from the surface, and a thickness is The present invention is characterized in that a single glass tape having a thickness of 0.5 mm to less than 1.0 mm is arranged so as to abut both the end of the water-cooled copper plate and the end of the steel plate .

According to the electroslag welding method of the present invention, it is possible to perform electroslag welding that can prevent melt leakage during welding and obtain a good weld bead without undercuts, so welding parts with good bead shapes can be made with high efficiency. Obtainable.

FIG. 1 is a diagram showing the groove shape of the electroslag welding method of the present invention. FIG. 2 is a diagram showing the groove shape of a conventional electroslag welding method.

In order to solve the above-mentioned problems, the present inventors have achieved a welded part that does not leak and has a good bead shape in electroslag welding in which the inside of a groove surrounded by a steel plate and a water-cooled copper plate is welded. Various welding methods were investigated. Specifically, various methods of eliminating gaps between the contact surfaces of the steel plates 1 and 2 and the water-cooled copper plates 3 and 4 were investigated. As a result, as shown in FIG. 1, the ends of the steel plates 1 and 2 on the water-cooled copper plate 3 side are replaced by the first end 1a and the first end 2a, and the ends of the steel plates 1 and 2 on the water-cooled copper plate 4 side, respectively. are a second end 1b and a second end 2b, respectively, and the ends of the water-cooled copper plate 3 and the water-cooled copper plate 4 on the steel plate 1 side are respectively a first end 3a and a first end 4a, a water-cooled copper plate 3 and a water-cooled copper plate 4, respectively. When the ends on the steel plate 2 side in By placing the glass tape T of a predetermined thickness between the end portion 1b and the first end portion 4a, and between the second end portion 2b and the second end portion 4b, the steel plate 1, the steel plate 2, the water-cooled copper plate 3, and the water-cooled It has been found that the gap between each contact surface with the copper plate 4 can be filled to prevent hot water from leaking.

In addition, by placing a glass tape T of a predetermined thickness between each abutting surface, when the glass tape T melts, each abutting surface between the steel plates 1 and 2 and the water-cooled copper plate 3 and the water-cooled copper plate 4 It has been found that by forming an appropriate gap between the beads and forming a slag in the gap, a good bead shape without undercuts can be obtained.

Note that the thickness of the glass tape T is 0.5 to 2.0 mm. By placing a glass tape T of a predetermined thickness between the contact surfaces of the steel plates 1 and 2 and the water-cooled copper plates 3 and 4, the steel plates 1 and 2 and the water-cooled copper plates 3 and 4 can be While preventing leakage of molten metal etc. from each contact surface, molten metal is caused to flow between the gap formed by the glass tape T placed between each contact surface and the end of the glass tape T to generate slag. Therefore, it is possible to prevent undercutting and improve the bead shape. If the thickness of the glass tape T is less than 0.5 mm, it will not be possible to fill the gaps between the contact surfaces that occur during assembly or welding of the test specimen, and molten metal will enter the gaps between the contact surfaces and cause metal leakage. is more likely to occur. Further, since the thickness of the slag generated in the gap where the glass tape T is melted is larger than the gap created when the glass tape T is melted, undercuts occur and the bead shape becomes defective. On the other hand, if the thickness of the glass tape T exceeds 2.0 mm, the distance between the steel plates 1 and 2 and the water-cooled copper plates 3 and 4 will become excessively large, resulting in excessive buildup at the end of the weld bead and The shape becomes worse. Therefore, the thickness of the glass tape T placed between each contact surface is set to 0.5 to 2.0 mm.

Note that there are no particular limitations on the material and size of the glass tape T placed between the contact surfaces, other than the thickness, but a general glass tape T containing SiO ₂ as a main component may be used. Further, the method of arranging the glass tape T is not particularly limited, but it may be attached to the steel plates 1 and 2 or the water-cooled copper plates 3 and 4 using adhesive glue.

Furthermore, the solid wire used is not particularly limited, but it is preferable to use a solid wire that complies with JIS Z 3353 YES52.

Further, the flux to be used is not particularly limited, but it is preferable to use a middle manganese oxide type melting type flux.

EXAMPLES Hereinafter, the effects of the present invention will be specifically explained with reference to Examples.

Two steel plates 1 and 2 with a thickness of 50 mm conforming to JIS Z 3106 SM490A are used, and the steel plates 1 and 2 are arranged in parallel with a 25 mm interval and the ends of the steel plates 1 and 2 are vertically butted against each other. After fixing restraining plates by welding to both sides of the steel plates 1 and 2, the test specimen is vertically brought into contact with the lower plate serving as a base, and fixed by welding. Next, two water-cooled copper plates 3 and 4 are placed on both sides of the steel plates 1 and 2 with a gap between them in a direction substantially perpendicular to the direction in which the steel plates butt. A glass tape T having the thickness shown in Table 1 is placed between each contact surface (at 4 locations), and each of the steel plates 1 and 2 and the water-cooled copper plates 3 and 4 are brought into contact with each other while sandwiching the placed glass tape T. After the surfaces are brought into contact, a wedge is inserted between the restraining plate hole and the water-cooled copper plates 3 and 4 to fix the water-cooled copper plates 3 and 4, thereby forming a groove 5.

Add molten flux in accordance with JIS Z 3353 FS-FG3 into the formed groove 5, insert a power supply nozzle, and feed out a welding wire with a wire diameter of 1.6 mm in accordance with JIS Z 3353 YES52. However, non-consumable nozzle type electroslag welding was carried out under the welding conditions shown in Table 2. Note that the height of the test specimen was 1000 mm.

The investigation items included visual inspection of the presence or absence of melt leakage during welding and the shape of the bead after welding. The results are summarized in Table 3.

Test No. in Table 3 1~Test No. 5 is an example of the present invention, test No. 6~Test No. 8 is a comparative example. Test No. which is an example of the present invention. 1~No. 5, glass tapes T are placed between the respective contact surfaces of the steel plates 1 and 2 and the water-cooled copper plates 3 and 4, and the thickness of each placed glass tape T is appropriate, so there is no leakage during electroslag welding. The results were extremely satisfactory, with no occurrence and the bead shape after welding was good.

Test No. in Comparative Example In No. 6, since the glass tape was thin, the gaps between the contact surfaces of the steel plates 1 and 2 and the water-cooled copper plates 3 and 4 could not be closed, and hot water leaked during welding. In addition, undercutting occurred in the weld bead, resulting in poor bead shape.

Test No. Sample No. 7 had a poor bead shape because the glass tape T was thick.

Test No. 8, since the glass tape T is not placed between the contact surfaces of the steel plates 1 and 2 and the water-cooled copper plates 3 and 4, the gaps between the contact surfaces of the steel plates 1 and 2 and the water-cooled copper plates 3 and 4 are It was not possible to seal it, and metal leakage occurred during welding. In addition, undercutting occurred in the weld bead, resulting in poor bead shape.

1 Steel plate 1a First end 1b Second end 2 Steel plate 2a First end 2b Second end 3 Water-cooled copper plate 3a First end 3b Second end 4 Water-cooled copper plate 4a First end 4b Second end 5 Bevel T Glass tape

Claims (1)

In an electroslag welding method, steel plates are abutted against each other vertically with a predetermined interval, the gap is sandwiched between water-cooled copper plates, and the inside of the groove surrounded by the steel plate and the water-cooled copper plate is welded. The water-cooled copper plate is arranged so that the groove is surrounded by a groove having a concave shape, and the water-cooled copper plate has a thickness of 0.5 mm to 1.5 mm on all contact surfaces between the end of the water-cooled copper plate and the end of the steel plate. An electroslag welding method characterized by arranging a single glass tape having a thickness of less than 0 mm and abutting both the end of the water-cooled copper plate and the end of the steel plate .

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