JPS6125464B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pipe butt welding method using TIG welding.

In TIG welding, as shown in Fig. 1, an arc is generated between a bare tungsten rod 1 and a workpiece 2 in an atmosphere of inert gas, and the heat is used to connect the filler metal 3 and workpiece 2. It performs welding while melting the material, and has the advantages of no coating or flux, easy welding in all positions, high efficiency, and excellent welding quality, and is widely used for metal welding.

In this TIG welding, as shown in Figure 2,
When welding butt portions of plates with a thickness of 1 to 3 mm, welding may be performed with an I-shaped groove with a root width of 0 and without using filler metal. This groove width is 0
When the pipe 2 is fixed horizontally as shown in Fig. 2 and welded by moving the TIG rod along the outer circumference of the pipe 2 as shown by the arrow, as shown in Figs. The molten metal 4 is pulled downward under the influence of gravity, and at the final completion an underbead a
There is a problem that occurs.

Therefore, as shown in Fig. 5, it is considered that a ring 5 is placed on the back of the welded part of the pipe 2, and this ring functions as both the conventional backing ring and the insert ring to prevent underbeat a. However, as shown by the chain line in the figure, there is a risk that the ring 5 will melt in the upper part and that part will come down and become an under bead a.

This invention is a TIG with zero groove width that does not use filler metal.
It is an object of the present invention to perform welding without causing underbeads even in welding.

In order to achieve this purpose, the present invention assumes that the molten metal is pulled downward by gravity, and melting is performed slightly above, so that the molten metal protrudes downward while being drawn downward. Next, this invention will be explained in detail based on FIGS. 6 and 7 showing one embodiment of the invention.

As shown in the figure, two horizontally positioned pipes 2 and 2 are butted against each other, and the abutting portion has a groove width of 0.
When performing TIG welding, a ring 10 is interposed between the butts of both pipes 2, 2, and the width t of this ring 10 is approximately the same as the pipe thickness T, and its outer diameter is the same as or slightly smaller than the pipe outer diameter. Big, for example +
Set the ring 10 to be about 0.5 mm larger, make the ring 10 slightly eccentric upwards from the center line of the pipe 2, move the TIG rod along the outer circumference of the pipe 2, and TIG both pipes 2 while melting the ring 10. Weld. The thickness P of the ring 10 is appropriately determined based on the thickness T of the pipe 2.

During this welding, welding is performed while the ring 10 and the abutting portions of both pipes 1 and 2 are melted, and the molten metal is pulled downward by gravity, but since the ring 10 has already shifted upward, the lowering causes the upper Protrusion in the outer diameter and lower inner diameter, depression in the lower outer diameter and upper inner diameter are corrected.

Therefore, according to the present invention, by eccentrically moving the ring upward and welding the ring while melting it, there is an effect that underbeat does not occur and highly accurate welding can be performed.

[Brief explanation of the drawing]

Figures 1 and 2 are front views showing the conventional TIG welding method, Figure 3 is an enlarged cutaway front view of the welded area by the conventional TIG welding method, Figure 4 is a side view of the same, and Figure 5 is a cutaway front view. , FIG. 6 is a front view showing the welding method of the present invention, and FIG. 7 is a sectional view taken along the line X--X in FIG. 6. 1... Tungsten rod, 2... Pipe (object to be welded), 3... Filler metal, 10... Ring.

Claims (1)

[Claims] 1 When two pipes placed horizontally are brought together and TIG welded at the butt part with a groove width of 0, a ring is inserted between the butts of both pipes, and the width of this ring is made to be approximately the same as the pipe thickness. At the same time, set its outside diameter to be the same as or slightly larger than the outside diameter of the pipe, make this ring slightly eccentric upwards from the center line of the pipe, move the TIG rod along the outside circumference of the pipe, and melt the ring while melting it. A pipe butt welding method characterized by welding both pipes.