JPS596748B2 - Flash butt welding method for thin-walled pipes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method of welding thin-walled pipes into a continuous pipe by flash butt welding, in which a protrusion such as a pin is attached to the pipe that the clamp contacts, and the pipe protrusion or pin This invention relates to a flash butt welding force method for thin-walled vibrators, which involves engaging a clamp to prevent slippage, obtaining an upset pressure, and then removing protrusions such as pins.

Conventionally, thin-walled pipes are welded continuously by arc welding, gas welding, brazing, etc., but in any case, the pipes are welded circumferentially, so the welding process is performed with the base metal as the axis. It is impossible to weld with high efficiency because it requires rotation, etc.

On the other hand, flash butt welding is a welding method in which the metal end faces on both sides to be joined are brought into light contact, heated through a large current to raise the temperature of the joint, and then rapidly applied pressure to perform upset welding.

However, the offset pressure of this flash butt welding is
For mild steel it is 4 to 79/mA) for stainless steel it is 7 to 13 kg/mA, and in order to obtain this upset pressure, the clamping force must be at least 5 times the upset pressure. However, thin-walled pipes cannot withstand the clamp pressure and deform, so it has been impossible to perform flash butt welding on thin-walled pipes that deform due to the clamp pressure. In the present invention, a projection such as a pin is attached to the outer circumference of the vibrator where the clamp of the thin-walled vibrator comes into contact, and the pipe projection or pin is engaged with the clamp to prevent slippage and obtain an absolute pressure. The purpose is to weld thin-walled pipes with high efficiency using flash butt welding. Next, embodiments of the present invention will be described with reference to the drawings.

Figures 1 to 5 each show the cross-sectional shape of the thin-walled vibrator, Figures 1 and 4 show the pins attached by welding or welding, and Figures 2, 3, and 5 show the pins attached by welding or welding. , shows a state in which a hole is made in the pipe and a pin is inserted into it. The shape of the thin-walled pipe is not limited to that shown in the drawings, and may be circular, oval, polygonal, thin-walled hollow material with a lip, etc., and is not particularly limited. There are no particular limitations on the length, thickness, etc. of the pin. The number of pins can be increased or decreased as appropriate depending on the strength of the material thickness of each vibrator and the absolute pressure so that the thin-walled pipe does not deform when absolute pressure is applied. Further, the pin may also be rod-shaped or plate-shaped.
FIG. 6 and FIG. T are side views showing the clamping situation.

1 is a thin-walled pipe and is welded with 4 and 5 facing each other.

Reference numeral 2 denotes a pin, and electrode molds 3 are located above and below, and clamp the thin-walled pipe 1.

The electrode mold 3 has a recess into which a pin is inserted, and one of the right and left electrode molds 3 is fixed, while the other is movable in the axial direction of the pipe, and by movement, it is possible to perform absolute pressure welding. Flash butt welding is carried out in the usual way, by lightly touching the metal end faces on both sides to be joined, and then passing a large current through this to intensively heat the contact point, which heats and melts and scatters as sparks. Once the contact is broken, the material to be welded is moved further forward and the temperature of the joint is increased by constantly repeating contact and spark scattering, and the welding end face is covered with metal vapor. When welding is performed by applying pressure, the clamping pressure is set to a level that does not deform the thin-walled vibrator, and since the clamp is engaged with the protrusion attached to the thin-walled pipe, the clamping pressure is not so great. Even if it is not strong, the thin-walled pipe will not shift and sufficient upset pressure can be obtained, enabling flash butt welding and welding of thin-walled vibrators.

Pins inserted after welding are removed at the same time as welding deburring. Also, pull out the inserted pin, fill the punched hole and weld if necessary, and remove the welding burr. As explained in detail above, in the present invention, a protrusion such as a pin is attached to a thin-walled pipe in advance and engaged with a clamp, so that sufficient offset pressure can be obtained without deforming the thin-walled pipe due to clamping pressure, and flat butt welding can be achieved. This makes it possible to achieve the following effects.

(1) The heating range is narrow and the thermal effect is small.

(2) A welded joint with high reliability and high joint strength can be obtained. (3) Power consumption is considerably lower than that of butt resistance welding.

(4) High efficiency.

[Brief explanation of the drawing]

FIGS. 1 to 5 are cross-sectional views of a thin-walled pipe with protrusions such as pins attached, and FIGS. 6 and 7 are cross-sectional views of the pipe in a clamped state. 1...Thin-walled pipe, 2...Pin, 3.
...Flash butt electrode type, 4 and 5...
...Welding surface.

Claims (1)

[Claims] 1. In a method of welding thin-walled pipes on the same axis to form a continuous pipe using flash butt welding, a protrusion such as a pin is welded or glued in advance to the outer circumference of the pipe where the clamp comes into contact, or A feature is that a hole is made and a pin is inserted, the protrusion or pin provided on the pipe is engaged with the clamp to prevent slippage, and welding is performed with upset pressure, and then the protrusion or pin is removed as necessary. Flash butt welding method for thin-walled pipes.