JPH03258466A - Butt welding method for flux-cored wires for welding - Google Patents

Abstract

PURPOSE:To prevent the outflow of flux and to obtain a welded and joined part having a good fused state by interposing iron foil between two wire ends to be joined to perform butt welding. CONSTITUTION:One wire 1 and the other wire 1' of wires 1 and 1' are held on a fixed electrode 5 and a movable electrode 5', respectively and the iron foil 3 is interposed between the wire end faces and the end faces are arranged properly and abutted on each other. An AC high current is then applied via the electrodes 5 and 5' and the vicinity of a weld zone is heated by resistance heat generation and when the proper high temperature is attained, the strong pressure is applied in the wire axial direction to joint the wires. A projection part 4 of weld metal is produced on the pipe outside of the joined part and the projection part 4 is removed by a grinder.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for butt welding a welding flux cored wire used in automatic or semi-automatic welding.

[Conventional technology]

Generally, in the wire drawing industry, when continuous work is performed by connecting wire rods, the area around the contact area is raised to the welding temperature by using heat generated by contact resistance and the specific resistance of the material by applying electricity.
Butt resistance welding, such as heart welding and flash welding, in which pressure is applied and crimping is used, is used. Flash welding is used for large cross-sectional areas that are difficult to butt weld, as well as thin-walled plates and pipes.Flash welding is used for welding wires that have small cross-sectional areas, and the equipment is simple and inexpensive, and the work can be performed easily and safely. Hunt welding is used, and butt welding machines of various capacities are used depending on the wire diameter. The procedure for welding wire is as follows: (1) Polish the surface of the wire and the end face of the material to be welded, align the end faces, and strongly butt them together.

(2) Apply electricity to heat the area around the welded area by resistance heat generation.

(3) Apply upset pressure using a spring, etc.

(4) After welding, remove the flash and perform annealing.

With this procedure, solid wire for welding can be welded without any problems.

However, the toughness of the welded metal inside the outer steel pipe during welding work, etc.
For welding flux-cored wires that are filled with flux that provides various necessary properties, if butt welding is performed in the same manner as for solid welding wires, the heat of butt welding will melt the filled flux. It becomes a slag,
Since it remains on the interface of the materials to be welded, fusion may be insufficient, causing trouble. Furthermore, irremovable burrs occur on the inner surface of the tube after welding, and these burrs often result in wire breakage when wire is drawn after hat welding. This is because the tube inside the tube is hard and is not drawn during the wire drawing process, so the wall thickness of the tube sandwiched between the die and the tube becomes thinner locally.

In order to solve this problem, there is a method of removing the flux at the ends of the two wires to be connected, and further limiting the length of the welding allowance, which directly affects the degree of fringing, to a predetermined length or less.

[Problem to be solved by the invention]

Adjusting this welding allowance is time-consuming and cannot be done easily, so it is extremely difficult to form a good welded joint while keeping the firmness to a level that does not cause any inconvenience in the wire drawing process after welding. It is. Furthermore, with this method, voids are created in the welded joint of the wire, which tends to result in poor strength.As a result, when drawing the wire, especially during reverse tension wire drawing, the wire joint stretches and collapses, resulting in different diameters. In product wires, buckling, bending, and polarization are likely to occur during wire feeding during welding, which may lead to poor feeding.

The present invention solves the above-mentioned conventional problems. In other words, it is possible to connect not only ordinary welding flux-cored wires, but also welding flux-cored wires such as seamed wires in which the outer steel pipe is a welded joint pipe, and seamless wires without seams, and the welding results are excellent. It is an object of the present invention to provide a hat welding method that has a positive effect on subsequent processes or usage conditions.

[Means to solve the problem]

The gist of the present invention to achieve this object is to provide a hat welding method for a flux-cored wire for welding, which is made by filling a sheathed steel pipe with flux, in which iron foil is placed between the ends of two wires to be connected. Butt welding is performed by intervening.

The material of the iron foil interposed at the end of the wire, that is, sandwiched, may have the same composition as the outer sheath steel of the wire, but in particular, for C, M, and 1, C: 0.001 to 0.10% M, 1:0° 1
A range of 5 to 0.50% is desirable. The thickness of the iron foil is preferably 0.01 to 0.25++ m. This is because when the thickness of the iron foil exceeds the upper limit of 0.25 mm, heat input is insufficient in a normal butt welder, causing poor fusion of the iron foil in contact with the outer skin, resulting in wire breakage during wire drawing. Also, if the thickness of the iron foil is less than the lower limit of 0.01 mm, it becomes difficult to handle during butt welding work.

[Effect]

In the present invention, the ends of two wires to be connected are sandwiched and butted with iron foil to prevent flux from flowing out.

Therefore, the flux is not heated and burned due to resistance heat during butt welding and becomes slag, and a welded joint with a good fusion state can be obtained. On the other hand, the iron foil sandwiched between both ends of the wire separates it)? It was found that the resistance heat of the wire due to energization during 8-contacting was transmitted only to the outer skin and did not reach the flux part.

Therefore, looking at the metal structure, the iron foil in the outer skin part is completely fused, whereas the iron foil in the flux part is not fused at all and has the same metal structure as iron foil. understood. For this reason, it is possible to prevent the flux from becoming slag due to heating and combustion, and the inner surface cracks have not developed.

This residual iron foil on the inner surface causes elongation equivalent to that of the outer steel pipe, so there was no problem when drawing the wire after welding the hat, and the drawability was significantly improved. In addition, the tedious work during work is eliminated, and hunt welding can now be easily performed without the need for special skills.

〔Example〕

The Hunt welding method of the present invention will be explained below according to specific examples shown in the drawings. Figures 1 to 4 are diagrams sequentially showing the process from the start to the end of hat welding. Figure 1 shows two wires l and 1' filled with flux 2゜2 for butt welding. It shows a state in which the ends are facing each other and the iron foil 3 is placed between them. In this way, prior to welding, wire 1,
Since the flux is prevented from flowing out by sandwiching the iron foil between the 1' ends, there is no problem caused by the flux turning into slag due to resistance heat of the wire due to energization.

Figure 2 shows wires 1 and 1' in the state shown in Figure 1, with one wire 1 held by a fixed electrode 5 and the other wire 1' held by a moving electrode 5', with an iron foil 3 interposed between the end faces of the wires. This shows a state in which they are aligned and butted together with their end surfaces aligned. and electrodes 5,5
A large alternating current is passed through the wire to heat the area around the welded area by resistance heat generation, and when the temperature reaches an appropriate high temperature, strong pressure is applied in the axial direction of the wire to join.

Figure 3 shows this joining state, and as a result of pressure joining, a raised part 4 of weld metal is formed on the outer surface of the pipe at the joint.
Due to the presence of the flux and the iron foil 3, virtually no protuberances are formed on the inner surface of the tube.

FIG. 4 shows a state in which the raised portion 4 on the outer surface of the tube has been removed using a grinder, and from this the wire 1. Finish the butt welding of l'.

〔Effect of the invention〕

In the present invention, when welding flux-cored wires are joined and then subjected to wire drawing processing, the diameter of the wire is reduced because there is no hardness inside the wire and instead there is iron foil with good ductility. At the same time, the joint is stretched, and the wire is drawn very well without causing any problems such as wire breakage. Furthermore, when the product wires are joined, the wires are then subjected to automatic or semi-automatic welding, but in order to prevent the flux from turning into slag, the present invention does not remove the flux and form voids as in the past. By welding with iron foil interposed, there is no need to remove the flux, so the iron foil is present together with the flux inside the wire at the joint.

As a result, in the present invention, the strength of the joint is superior to that in the case where a gap is simply provided, and the resistance in the coduit tube when feeding the wire during welding, the buckling and bending of the wire due to the feeding roller, etc. The wire is fed very smoothly without any problems such as polarization, and the welding portion exhibits almost the same welding performance as other wire portions, so that good welding can be achieved.

[Brief explanation of drawings]

FIGS. 1 to 4 are explanatory diagrams showing the butt welding procedure of the present invention. In the drawing, 1 and 1' are wires, 2 is flux, 3 is iron foil,
4 is a raised portion on the outer surface of the tube, and 5.5' is an electrode. 3: Steel foil Figure 1 Applicant: Nippon Steel Welding Industry Co., Ltd.

Claims (1)

[Claims] 1. A method of butt welding a flux-cored wire for welding, which is made by filling a sheathed steel pipe with flux, and is characterized by butt welding with iron foil interposed between the ends of two wires to be connected. Butt welding method for welding flux-cored wire.